I set my exposure to slide the histogram to the right, without clipping
( when I have time), to capture the most tonal levels . So, now when I
am editing the photos they are over exposed(not clipped). A sunrise is
a good example. The deep colors are washed out. The obvious fix(to me
anyway) in Lightroom or CS4 is to reduce the exposure. Now my question
is, by reducing exposure in post, am I just ending up in the same place
(histogram to the left) as if I had just ignored the histogram when I
was shooting and set the exposure to properly expose the image using
my light meter? I guess in short I am asking if Lightroom or CS4 loses
tonal values when you reduce exposure in editing.


Porte

Porte Rouge wrote:
> I set my exposure to slide the histogram to the right, without clipping
> ( when I have time), to capture the most tonal levels . So, now when I
> am editing the photos they are over exposed(not clipped). A sunrise is
> a good example. The deep colors are washed out. The obvious fix(to me
> anyway) in Lightroom or CS4 is to reduce the exposure. Now my question
> is, by reducing exposure in post, am I just ending up in the same place
> (histogram to the left) as if I had just ignored the histogram when I
> was shooting and set the exposure to properly expose the image using
> my light meter? I guess in short I am asking if Lightroom or CS4 loses
> tonal values when you reduce exposure in editing.
> 
> 
> Porte

There is no simple answer. It depends on whether you shoot raw
or jpeg, and whether you use 8 or 16 bits in Photoshop.

If you shoot raw and go to 16 bits in Photoshop you will indeed
capture more tonal levels and better shadow detail if you correctly
set the histogram in the camera as far right as possible. Significant
improvements in shadow detail are possible compared to "politically
correct" exposure in the camera.

If you use jpeg and 8 bits, maybe, maybe not.

Doug McDonald

On Oct 4, 9:40=A0am, Doug McDonald
<mcdon...@scs.uiuc.edu.remove.invalid> wrote:
> Porte Rouge wrote:
> > I set my exposure to slide the histogram to the right, without clipping
> > ( when I have time), to capture the most tonal levels . So, now when I
> > am editing the photos they are over exposed(not clipped). A sunrise is
> > a good example. The deep colors are washed out. The obvious fix(to me
> > anyway) in Lightroom or CS4 is to reduce the exposure. Now my question
> > is, by reducing exposure in post, am I just ending up in the same place
> > (histogram to the left) as if I had just ignored the histogram when I
> > was shooting and set the exposure to properly expose the image using
> > my light meter? I guess in short I am asking if Lightroom or CS4 loses
> > tonal values when you reduce exposure in editing.
>
> > Porte
>
> There is no simple answer. It depends on whether you shoot raw
> or jpeg, and whether you use 8 or 16 bits in Photoshop.
>
> If you shoot raw and go to 16 bits in Photoshop you will indeed
> capture more tonal levels and better shadow detail if you correctly
> set the histogram in the camera as far right as possible. Significant
> improvements in shadow detail are possible compared to "politically
> correct" exposure in the camera.
>
> If you use jpeg and 8 bits, maybe, maybe not.
>
> Doug McDonald

I shoot RAW and edit in 16 bit. That's interesting. I take it that
reducing exposure in 16 bit preserves tonal levels because there are
more levels in 16 bit. Or is there some other pixel black magic going
on?


Porte

On Oct 4, 9:40=A0am, Doug McDonald
<mcdon...@scs.uiuc.edu.remove.invalid> wrote:
> Porte Rouge wrote:
> > I set my exposure to slide the histogram to the right, without clipping
> > ( when I have time), to capture the most tonal levels . So, now when I
> > am editing the photos they are over exposed(not clipped). A sunrise is
> > a good example. The deep colors are washed out. The obvious fix(to me
> > anyway) in Lightroom or CS4 is to reduce the exposure. Now my question
> > is, by reducing exposure in post, am I just ending up in the same place
> > (histogram to the left) as if I had just ignored the histogram when I
> > was shooting and set the exposure to properly expose the image using
> > my light meter? I guess in short I am asking if Lightroom or CS4 loses
> > tonal values when you reduce exposure in editing.
>
> > Porte
>
> There is no simple answer. It depends on whether you shoot raw
> or jpeg, and whether you use 8 or 16 bits in Photoshop.
>
> If you shoot raw and go to 16 bits in Photoshop you will indeed
> capture more tonal levels and better shadow detail if you correctly
> set the histogram in the camera as far right as possible. Significant
> improvements in shadow detail are possible compared to "politically
> correct" exposure in the camera.
>
> If you use jpeg and 8 bits, maybe, maybe not.
>
> Doug McDonald

I shoot RAW and edit in 16 bit. That's interesting. I take it that
reducing exposure in 16 bit preserves tonal levels because there are
more levels in 16 bit. Or is there some other pixel black magic going
on?

Porte

On Sun, 4 Oct 2009 06:25:12 -0700 (PDT), Porte Rouge
<porterougeman@gmail.com> wrote:

>I set my exposure to slide the histogram to the right, without clipping
>( when I have time), to capture the most tonal levels . So, now when I
>am editing the photos they are over exposed(not clipped). A sunrise is
>a good example. The deep colors are washed out. The obvious fix(to me
>anyway) ...

.... doesn't seem to be obvious to you. Instead of learning how to expose
each scene properly and not rely on dumbed-down point and shoot
snapshooter's suggestions (like "expose to the right", which only applies
to very few subjects) or depending on your automatic point and shoot modes
of your camera, you'll forever be wasting your time in editing instead of
taking photos the right way to begin with.

This is what you get for taking to heart the lame "one size fits all"
dumbed-down snapshooters suggestions made by all point 'n shooters and
armchair photographers on the net.

taylor aldler wrote:
> On Sun, 4 Oct 2009 06:25:12 -0700 (PDT), Porte Rouge
> <porterougeman@gmail.com> wrote:
> 
>> I set my exposure to slide the histogram to the right, without clipping
>> ( when I have time), to capture the most tonal levels . So, now when I
>> am editing the photos they are over exposed(not clipped). A sunrise is
>> a good example. The deep colors are washed out. The obvious fix(to me
>> anyway) ...
> 
> ... doesn't seem to be obvious to you. Instead of learning how to expose
> each scene properly and not rely on dumbed-down point and shoot
> snapshooter's suggestions (like "expose to the right", which only applies
> to very few subjects) or depending on your automatic point and shoot modes
> of your camera, you'll forever be wasting your time in editing instead of
> taking photos the right way to begin with.

Why do you question a proven technique that lifts shadows into noise 
free detail?  Really, let people do their thing for their purposes ... 
better than criticizing without showing your own prowess.

Porte Rouge wrote:
> I set my exposure to slide the histogram to the right, without clipping
> ( when I have time), to capture the most tonal levels . So, now when I
> am editing the photos they are over exposed(not clipped). A sunrise is
> a good example. The deep colors are washed out. The obvious fix(to me
> anyway) in Lightroom or CS4 is to reduce the exposure. Now my question
> is, by reducing exposure in post, am I just ending up in the same place
> (histogram to the left) as if I had just ignored the histogram when I
> was shooting and set the exposure to properly expose the image using
> my light meter? I guess in short I am asking if Lightroom or CS4 loses
> tonal values when you reduce exposure in editing.
> 
> 
> Porte
For me, digital is the opposite of film in exposure emphasis.
In film, you expose for the shadows, while in digital you should expose 
for the highlights.
You can't print underexposed shadows on a film negative but you can burn 
in overexposed highlights since the negatives tend to hold some 
information in that area.
You can't print overexposed highlights in a digital image but you can 
tease out information from underexposed shadows in digital processing.
You can't treat your entire image the same way, so you need to apply 
techniques similar to dodging and burning in the digital realm using 
area adjustments of an image and the various tools/techniques available 
in image editors.

taylor aldler wrote:
> On Sun, 4 Oct 2009 06:25:12 -0700 (PDT), Porte Rouge
> <porterougeman@gmail.com> wrote:
> 
>> I set my exposure to slide the histogram to the right, without clipping
>> ( when I have time), to capture the most tonal levels . So, now when I
>> am editing the photos they are over exposed(not clipped). A sunrise is
>> a good example. The deep colors are washed out. The obvious fix(to me
>> anyway) ...
> 
> ... doesn't seem to be obvious to you. Instead of learning how to expose
> each scene properly and not rely on dumbed-down point and shoot
> snapshooter's suggestions (like "expose to the right", which only applies
> to very few subjects) or depending on your automatic point and shoot modes
> of your camera, you'll forever be wasting your time in editing instead of
> taking photos the right way to begin with.
> 
> This is what you get for taking to heart the lame "one size fits all"
> dumbed-down snapshooters suggestions made by all point 'n shooters and
> armchair photographers on the net.
> 


This sounds like the P&S troll.

"Exposing for jpeg" which is what he proposes is NOT
the absolute best way to use a more capable camera like a dSLR.

That is, indeed, to expose for the highlights, putting them
just under the clipping value, and save as raw. Fix later
in the raw->jpeg conversion.

Doug

On Sun, 04 Oct 2009 10:17:25 -0500, Doug McDonald wrote:

>> ... doesn't seem to be obvious to you. Instead of learning how to
>> expose each scene properly and not rely on dumbed-down point and shoot
>> snapshooter's suggestions (like "expose to the right", which only
>> applies to very few subjects) or depending on your automatic point and
>> shoot modes of your camera, you'll forever be wasting your time in
>> editing instead of taking photos the right way to begin with.
>> 
>> This is what you get for taking to heart the lame "one size fits all"
>> dumbed-down snapshooters suggestions made by all point 'n shooters and
>> armchair photographers on the net.
> 
> This sounds like the P&S troll.
> 
> "Exposing for jpeg" which is what he proposes is NOT the absolute best
> way to use a more capable camera like a dSLR.
> 
> That is, indeed, to expose for the highlights, putting them just under
> the clipping value, and save as raw. Fix later in the raw->jpeg
> conversion.

Your method is not the absolute best way either. There is no absolute 
best way.

-- 
Regards, Robert                                      http://www.arumes.com

Luis Ortega wrote:
> Porte Rouge wrote:
>> I set my exposure to slide the histogram to the right, without clipping
>> ( when I have time), to capture the most tonal levels . So, now when I
>> am editing the photos they are over exposed(not clipped). A sunrise is
>> a good example. The deep colors are washed out. The obvious fix(to me
>> anyway) in Lightroom or CS4 is to reduce the exposure. Now my question
>> is, by reducing exposure in post, am I just ending up in the same place
>> (histogram to the left) as if I had just ignored the histogram when I
>> was shooting and set the exposure to properly expose the image using
>> my light meter? I guess in short I am asking if Lightroom or CS4 loses
>> tonal values when you reduce exposure in editing.
>>
>>
>> Porte
> For me, digital is the opposite of film in exposure emphasis.
> In film, you expose for the shadows, while in digital you should expose 
> for the highlights.

In negative film you expose for the shadows.

In positive (reversal, slide) film you expose for highlight placement.

In this sense digital behaves much like slide film except for a little 
more shadow detail.

Doug McDonald wrote:
> taylor aldler wrote:
>> On Sun, 4 Oct 2009 06:25:12 -0700 (PDT), Porte Rouge
>> <porterougeman@gmail.com> wrote:
>>
>>> I set my exposure to slide the histogram to the right, without clipping
>>> ( when I have time), to capture the most tonal levels . So, now when I
>>> am editing the photos they are over exposed(not clipped). A sunrise is
>>> a good example. The deep colors are washed out. The obvious fix(to me
>>> anyway) ...
>>
>> ... doesn't seem to be obvious to you. Instead of learning how to expose
>> each scene properly and not rely on dumbed-down point and shoot
>> snapshooter's suggestions (like "expose to the right", which only applies
>> to very few subjects) or depending on your automatic point and shoot 
>> modes
>> of your camera, you'll forever be wasting your time in editing instead of
>> taking photos the right way to begin with.
>>
>> This is what you get for taking to heart the lame "one size fits all"
>> dumbed-down snapshooters suggestions made by all point 'n shooters and
>> armchair photographers on the net.
>>
> 
> 
> This sounds like the P&S troll.
> 
> "Exposing for jpeg" which is what he proposes is NOT
> the absolute best way to use a more capable camera like a dSLR.
> 
> That is, indeed, to expose for the highlights, putting them
> just under the clipping value, and save as raw. Fix later
> in the raw->jpeg conversion.

Actually do what you say on import of raw into the editor (say photoshop 
ACR) and maintain it as 16 bit/colour for all edits before saving in any 
other format, including JPG's.

Doug McDonald wrote:
> taylor aldler wrote:
>> On Sun, 4 Oct 2009 06:25:12 -0700 (PDT), Porte Rouge
>> <porterougeman@gmail.com> wrote:
>>
>>> I set my exposure to slide the histogram to the right, without clipping
>>> ( when I have time), to capture the most tonal levels . So, now when I
>>> am editing the photos they are over exposed(not clipped). A sunrise is
>>> a good example. The deep colors are washed out. The obvious fix(to me
>>> anyway) ...
>>
>> ... doesn't seem to be obvious to you. Instead of learning how to expose
>> each scene properly and not rely on dumbed-down point and shoot
>> snapshooter's suggestions (like "expose to the right", which only applies
>> to very few subjects) or depending on your automatic point and shoot 
>> modes
>> of your camera, you'll forever be wasting your time in editing instead of
>> taking photos the right way to begin with.
>>
>> This is what you get for taking to heart the lame "one size fits all"
>> dumbed-down snapshooters suggestions made by all point 'n shooters and
>> armchair photographers on the net.
>>
> 
> 
> This sounds like the P&S troll.
> 
> "Exposing for jpeg" which is what he proposes is NOT
> the absolute best way to use a more capable camera like a dSLR.
> 
> That is, indeed, to expose for the highlights, putting them
> just under the clipping value, and save as raw. Fix later
> in the raw->jpeg conversion.

And by the way, allowing some highlights to clip (direct lighting, some 
specular reflections) is quite alright, otherwise you'll push the middle 
down into the shadows and increase noise.

This is where good spot metering skills come in.

On Oct 4, 11:39=A0am, Robert Spanjaard <spamt...@arumes.com> wrote:
> On Sun, 04 Oct 2009 10:17:25 -0500, Doug McDonald wrote:
> >> ... doesn't seem to be obvious to you. Instead of learning how to
> >> expose each scene properly and not rely on dumbed-down point and shoot
> >> snapshooter's suggestions (like "expose to the right", which only
> >> applies to very few subjects) or depending on your automatic point and
> >> shoot modes of your camera, you'll forever be wasting your time in
> >> editing instead of taking photos the right way to begin with.
>
> >> This is what you get for taking to heart the lame "one size fits all"
> >> dumbed-down snapshooters suggestions made by all point 'n shooters and
> >> armchair photographers on the net.
>
> > This sounds like the P&S troll.
>
> > "Exposing for jpeg" which is what he proposes is NOT the absolute best
> > way to use a more capable camera like a dSLR.
>
> > That is, indeed, to expose for the highlights, putting them just under
> > the clipping value, and save as raw. Fix later in the raw->jpeg
> > conversion.
>
> Your method is not the absolute best way either. There is no absolute
> best way.
>
> --
> Regards, Robert =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 =A0 =A0 =A0http://www.arumes.com

   Do you have more to say about which way you set exposure and when?
I am genuinely interested in how you decide to set exposure. At this
point I actually use both, "expose to the right" and light meter, for
the "fine art" shots. I can't see a difference, I was just curious in
a CD versus vinyl sort of way.

Porte

On Sun, 04 Oct 2009 10:17:25 -0500, Doug McDonald
<mcdonald@scs.uiuc.edu.remove.invalid> wrote:

>taylor aldler wrote:
>> On Sun, 4 Oct 2009 06:25:12 -0700 (PDT), Porte Rouge
>> <porterougeman@gmail.com> wrote:
>> 
>>> I set my exposure to slide the histogram to the right, without clipping
>>> ( when I have time), to capture the most tonal levels . So, now when I
>>> am editing the photos they are over exposed(not clipped). A sunrise is
>>> a good example. The deep colors are washed out. The obvious fix(to me
>>> anyway) ...
>> 
>> ... doesn't seem to be obvious to you. Instead of learning how to expose
>> each scene properly and not rely on dumbed-down point and shoot
>> snapshooter's suggestions (like "expose to the right", which only applies
>> to very few subjects) or depending on your automatic point and shoot modes
>> of your camera, you'll forever be wasting your time in editing instead of
>> taking photos the right way to begin with.
>> 
>> This is what you get for taking to heart the lame "one size fits all"
>> dumbed-down snapshooters suggestions made by all point 'n shooters and
>> armchair photographers on the net.
>> 
>
>
>This sounds like the P&S troll.

It is.

>"Exposing for jpeg" which is what he proposes is NOT
>the absolute best way to use a more capable camera like a dSLR.
>
>That is, indeed, to expose for the highlights, putting them
>just under the clipping value, and save as raw. Fix later
>in the raw->jpeg conversion.
>
>Doug

On Sun, 4 Oct 2009 06:25:12 -0700 (PDT), Porte Rouge
<porterougeman@gmail.com> wrote:

>I set my exposure to slide the histogram to the right, without clipping
>( when I have time), to capture the most tonal levels . So, now when I
>am editing the photos they are over exposed(not clipped). A sunrise is
>a good example. The deep colors are washed out. The obvious fix(to me
>anyway) in Lightroom or CS4 is to reduce the exposure. Now my question
>is, by reducing exposure in post, am I just ending up in the same place
>(histogram to the left) as if I had just ignored the histogram when I
>was shooting and set the exposure to properly expose the image using
>my light meter? I guess in short I am asking if Lightroom or CS4 loses
>tonal values when you reduce exposure in editing.

You overexpose short of clipping, the apply a likewise (if preferred)
reverse adjustment in post. This is to maximize the signal-to-noise
and tonal gradations in the exposure.

The tonal aspect is analogous to setting a digital multimeter to the
proper scale before taking a reading, in order to maximize the
significant digits.

In article <1gkhc5hsgi6fasjanur2a0ojc5v03thhrp@4ax.com>,
John A.  <john@nowhere.invalid> wrote:
>On Sun, 4 Oct 2009 06:25:12 -0700 (PDT), Porte Rouge
><porterougeman@gmail.com> wrote:
>
>>I set my exposure to slide the histogram to the right, without clipping
>>( when I have time), to capture the most tonal levels . So, now when I
>>am editing the photos they are over exposed(not clipped). A sunrise is
>>a good example. The deep colors are washed out. The obvious fix(to me
>>anyway) in Lightroom or CS4 is to reduce the exposure. Now my question
>>is, by reducing exposure in post, am I just ending up in the same place
>>(histogram to the left) as if I had just ignored the histogram when I
>>was shooting and set the exposure to properly expose the image using
>>my light meter? I guess in short I am asking if Lightroom or CS4 loses
>>tonal values when you reduce exposure in editing.
>
>You overexpose short of clipping, the apply a likewise (if preferred)
>reverse adjustment in post. This is to maximize the signal-to-noise
>and tonal gradations in the exposure.
>
>The tonal aspect is analogous to setting a digital multimeter to the
>proper scale before taking a reading, in order to maximize the
>significant digits.


This blog article talks about making the best of exposing to the
right.

http://www.luminous-landscape.com/tutorials/right-hista.shtml
-- 
Al Dykes
 News is something someone wants to suppress, everything else is advertising.
    - Lord Northcliffe, publisher of the Daily Mail

Al Dykes wrote:
> In article <1gkhc5hsgi6fasjanur2a0ojc5v03thhrp@4ax.com>,
> John A.  <john@nowhere.invalid> wrote:
>> On Sun, 4 Oct 2009 06:25:12 -0700 (PDT), Porte Rouge
>> <porterougeman@gmail.com> wrote:
>>
>>> I set my exposure to slide the histogram to the right, without clipping
>>> ( when I have time), to capture the most tonal levels . So, now when I
>>> am editing the photos they are over exposed(not clipped). A sunrise is
>>> a good example. The deep colors are washed out. The obvious fix(to me
>>> anyway) in Lightroom or CS4 is to reduce the exposure. Now my question
>>> is, by reducing exposure in post, am I just ending up in the same place
>>> (histogram to the left) as if I had just ignored the histogram when I
>>> was shooting and set the exposure to properly expose the image using
>>> my light meter? I guess in short I am asking if Lightroom or CS4 loses
>>> tonal values when you reduce exposure in editing.
>> You overexpose short of clipping, the apply a likewise (if preferred)
>> reverse adjustment in post. This is to maximize the signal-to-noise
>> and tonal gradations in the exposure.
>>
>> The tonal aspect is analogous to setting a digital multimeter to the
>> proper scale before taking a reading, in order to maximize the
>> significant digits.
> 
> 
> This blog article talks about making the best of exposing to the
> right.
> 
> http://www.luminous-landscape.com/tutorials/right-hista.shtml

And the previous article linked from there explains how the significant 
digits benefit works:
http://www.luminous-landscape.com/tutorials/expose-right.shtml

-- 
Paul Furman
www.edgehill.net
www.baynatives.com

all google groups messages filtered due to spam

Porte Rouge wrote:

> 
>    Do you have more to say about which way you set exposure and when?
> I am genuinely interested in how you decide to set exposure. At this
> point I actually use both, "expose to the right" and light meter, for
> the "fine art" shots. I can't see a difference, I was just curious in
> a CD versus vinyl sort of way.
> 

It is experience, about when it matters to get the highlights just exactly
"right", which does as someone mentioned including correctly clipping the
ultra bright things like specular reflections and lamps.

I am mainly concerned with clouds in landscapes. Clipping
those can lead to really bad results at times.

When the going gets tough in such cases (landscapes) the Photoshop
Highlight/shadow tool is the critical one. But it takes practice.

Doug McDonald

Porte Rouge wrote:

>    Do you have more to say about which way you set exposure and when?


One more thing about histograms in the camera: at least in Canons,
they are made from the in-camera jpeg! This means that to make them
useful, you have to set the camera to make jpegs using "faithful"
mode, and contrast set to -3 or -4. Even so, it is only approximate.
You also need to use the "flashing overload" indicator on the
camera review screen. If you set contrast to 0 or more (remember, this is Canon)
and trust the histogram, you will still lose dynamic range.

Experience.

Doug McDonald

On Oct 4, 1:52=A0pm, Doug McDonald
<mcdon...@scs.uiuc.edu.remove.invalid> wrote:
> Porte Rouge wrote:
> > =A0 =A0Do you have more to say about which way you set exposure and whe=
n?
>
> One more thing about histograms in the camera: at least in Canons,
> they are made from the in-camera jpeg!

Do you know if this is true of  the Nikon D200?


 This means that to make them
> useful, you have to set the camera to make jpegs using "faithful"
> mode,

I'm sorry, what is "faithful" mode?

 and contrast set to -3 or -4. Even so, it is only approximate.
> You also need to use the "flashing overload" indicator on the
> camera review screen. If you set contrast to 0 or more (remember, this is=
 Canon)
> and trust the histogram, you will still lose dynamic range.
>
> Experience.
>
> Doug McDonald

   I use the flashing overload indicator, too. It sounds like I need
to do some test shots and see if clipped in the camera LCD is clipped
in ACR or Lightroom.

On Oct 4, 12:34=A0pm, Alan Browne <alan.bro...@FreelunchVideotron.ca>
wrote:
> Doug McDonald wrote:
> > taylor aldler wrote:
> >> On Sun, 4 Oct 2009 06:25:12 -0700 (PDT), Porte Rouge
> >> <porterouge...@gmail.com> wrote:
>
> >>> I set my exposure to slide the histogram to the right, without clippi=
ng
> >>> ( when I have time), to capture the most tonal levels . So, now when =
I
> >>> am editing the photos they are over exposed(not clipped). A sunrise i=
s
> >>> a good example. The deep colors are washed out. The obvious fix(to me
> >>> anyway) ...
>
> >> ... doesn't seem to be obvious to you. Instead of learning how to expo=
se
> >> each scene properly and not rely on dumbed-down point and shoot
> >> snapshooter's suggestions (like "expose to the right", which only appl=
ies
> >> to very few subjects) or depending on your automatic point and shoot
> >> modes
> >> of your camera, you'll forever be wasting your time in editing instead=
 of
> >> taking photos the right way to begin with.
>
> >> This is what you get for taking to heart the lame "one size fits all"
> >> dumbed-down snapshooters suggestions made by all point 'n shooters and
> >> armchair photographers on the net.
>
> > This sounds like the P&S troll.
>
> > "Exposing for jpeg" which is what he proposes is NOT
> > the absolute best way to use a more capable camera like a dSLR.
>
> > That is, indeed, to expose for the highlights, putting them
> > just under the clipping value, and save as raw. Fix later
> > in the raw->jpeg conversion.
>
> And by the way, allowing some highlights to clip (direct lighting, some
> specular reflections) is quite alright, otherwise you'll push the middle
> down into the shadows and increase noise.

 That is a good point. I hadn't thought of that.

> This is where good spot metering skills come in.

On Sun, 4 Oct 2009 16:49:29 -0700 (PDT), Porte Rouge
<porterougeman@gmail.com> wrote:

>On Oct 4, 1:52�pm, Doug McDonald
><mcdon...@scs.uiuc.edu.remove.invalid> wrote:
>> Porte Rouge wrote:
>> > � �Do you have more to say about which way you set exposure and when?
>>
>> One more thing about histograms in the camera: at least in Canons,
>> they are made from the in-camera jpeg!
>
>Do you know if this is true of  the Nikon D200?
>
>
> This means that to make them
>> useful, you have to set the camera to make jpegs using "faithful"
>> mode,
>
>I'm sorry, what is "faithful" mode?

You may want to look at this page on uniWB (Unitary White Balance):
http://www.guillermoluijk.com/tutorial/uniwb/index_en.htm

> and contrast set to -3 or -4. Even so, it is only approximate.
>> You also need to use the "flashing overload" indicator on the
>> camera review screen. If you set contrast to 0 or more (remember, this is Canon)
>> and trust the histogram, you will still lose dynamic range.
>>
>> Experience.
>>
>> Doug McDonald
>
>   I use the flashing overload indicator, too. It sounds like I need
>to do some test shots and see if clipped in the camera LCD is clipped
>in ACR or Lightroom.

On Oct 4, 1:10=A0pm, ady...@panix.com (Al Dykes) wrote:
> In article <1gkhc5hsgi6fasjanur2a0ojc5v03th...@4ax.com>,
> John A. =A0<j...@nowhere.invalid> wrote:
>
>
>
> >On Sun, 4 Oct 2009 06:25:12 -0700 (PDT), Porte Rouge
> ><porterouge...@gmail.com> wrote:
>
> >>I set my exposure to slide the histogram to the right, without clipping
> >>( when I have time), to capture the most tonal levels . So, now when I
> >>am editing the photos they are over exposed(not clipped). A sunrise is
> >>a good example. The deep colors are washed out. The obvious fix(to me
> >>anyway) in Lightroom or CS4 is to reduce the exposure. Now my question
> >>is, by reducing exposure in post, am I just ending up in the same place
> >>(histogram to the left) as if I had just ignored the histogram when I
> >>was shooting and set the exposure to properly expose the image using
> >>my light meter? I guess in short I am asking if Lightroom or CS4 loses
> >>tonal values when you reduce exposure in editing.
>
> >You overexpose short of clipping, the apply a likewise (if preferred)
> >reverse adjustment in post. This is to maximize the signal-to-noise
> >and tonal gradations in the exposure.
>
> >The tonal aspect is analogous to setting a digital multimeter to the
> >proper scale before taking a reading, in order to maximize the
> >significant digits.
>
> This blog article talks about making the best of exposing to the
> right.
>
> http://www.luminous-landscape.com/tutorials/right-hista.shtml
> --
> Al Dykes
> =A0News is something someone wants to suppress, everything else is advert=
ising.
> =A0 =A0 - Lord Northcliffe, publisher of the Daily Mail

   Wow, good stuff. I had to run out and get my camera and check the
settings. I don't understand what he says about the white balance. I
have it set on auto and have ignored it when shooting RAW. Should I
adjust it for each lighting condition when I shoot and this will give
me a truer histogram?

Porte

On Sun, 4 Oct 2009 09:47:45 -0700 (PDT), Porte Rouge
<porterougeman@gmail.com> wrote:

>On Oct 4, 11:39�am, Robert Spanjaard <spamt...@arumes.com> wrote:
>> On Sun, 04 Oct 2009 10:17:25 -0500, Doug McDonald wrote:
>> >> ... doesn't seem to be obvious to you. Instead of learning how to
>> >> expose each scene properly and not rely on dumbed-down point and shoot
>> >> snapshooter's suggestions (like "expose to the right", which only
>> >> applies to very few subjects) or depending on your automatic point and
>> >> shoot modes of your camera, you'll forever be wasting your time in
>> >> editing instead of taking photos the right way to begin with.
>>
>> >> This is what you get for taking to heart the lame "one size fits all"
>> >> dumbed-down snapshooters suggestions made by all point 'n shooters and
>> >> armchair photographers on the net.
>>
>> > This sounds like the P&S troll.
>>
>> > "Exposing for jpeg" which is what he proposes is NOT the absolute best
>> > way to use a more capable camera like a dSLR.
>>
>> > That is, indeed, to expose for the highlights, putting them just under
>> > the clipping value, and save as raw. Fix later in the raw->jpeg
>> > conversion.
>>
>> Your method is not the absolute best way either. There is no absolute
>> best way.
>>
>> --
>> Regards, Robert � � � � � � � � � � � � � � � � � � �http://www.arumes.com
>
>   Do you have more to say about which way you set exposure and when?
>I am genuinely interested in how you decide to set exposure. At this
>point I actually use both, "expose to the right" and light meter, for
>the "fine art" shots. I can't see a difference, I was just curious in
>a CD versus vinyl sort of way.
>
>Porte

There IS NO ONE RIGHT WAY. Not even a cut 'n dried dozen right ways. Each
and every photograph requires a unique way to expose it properly. No
automated metering system in the world will ever get it right for you.
Unless you are like most people, a point 'n shooter, wanting some tech-head
in a computer lab trying to decide your exposures for you the rest of your
life. The metering recommendation designed and programmed by someone who's
never taken one photo in their life. Or even worse, if you depend on the
advice of all those armchair photographers that infest the net and
newsgroups. Those desperately pretending to be photographers, laughing to
themselves when they find out they managed to convince someone to do as
they told you to do, never having held even one camera in their own
lifetime. And you all fall for it like the fools that you are.

This is why I find a live-view display (EVF or LCD) so valuable today. I
can instantly see that I have to lower the exposure of a sunrise or sunset
by as much as 2.5-3.0 EV stops to properly capture the intense colors and
dramatic cloud contrasts. I can instantly see why I have to overexpose the
scene on the water by up to 1.5 EV steps or more and let all those
highlights on the water go out completely. I can instantly see that in
order to capture the moon's features while it's rising above that mountain
peak that I'll have to underexpose by 4 or more stops, ambient light
depending.

If you are depending on your metering system, depending on some lame-assed
one-size-fits-all amateur's recommendation of "always expose to the right",
and all the other inane nonsense of theirs, it will only keep you glued to
your editor trying to desperately repair what you failed to do right in the
first place. Never getting it quite right in editing, ever, no matter what
you do. RAW file or not. I shoot with RAW files and I NEVER use that lame
beginner snapshooter's recommendation of "expose to the right".

Photography (digital especially) may be greatly depending on science, but
it is all art. 100% art. There's no one right color of oil-paints, no one
right medium, no one right brush, no one right way to create a
brush-stroke. ...

Get your heads out of your collective tech-head's asses.

On Oct 4, 11:06=A0pm, taylor aldler <tald...@nospam.org> wrote:
> On Sun, 4 Oct 2009 09:47:45 -0700 (PDT), Porte Rouge
>
>
>
> <porterouge...@gmail.com> wrote:
> >On Oct 4, 11:39=A0am, Robert Spanjaard <spamt...@arumes.com> wrote:
> >> On Sun, 04 Oct 2009 10:17:25 -0500, Doug McDonald wrote:
> >> >> ... doesn't seem to be obvious to you. Instead of learning how to
> >> >> expose each scene properly and not rely on dumbed-down point and sh=
oot
> >> >> snapshooter's suggestions (like "expose to the right", which only
> >> >> applies to very few subjects) or depending on your automatic point =
and
> >> >> shoot modes of your camera, you'll forever be wasting your time in
> >> >> editing instead of taking photos the right way to begin with.
>
> >> >> This is what you get for taking to heart the lame "one size fits al=
l"
> >> >> dumbed-down snapshooters suggestions made by all point 'n shooters =
and
> >> >> armchair photographers on the net.
>
> >> > This sounds like the P&S troll.
>
> >> > "Exposing for jpeg" which is what he proposes is NOT the absolute be=
st
> >> > way to use a more capable camera like a dSLR.
>
> >> > That is, indeed, to expose for the highlights, putting them just und=
er
> >> > the clipping value, and save as raw. Fix later in the raw->jpeg
> >> > conversion.
>
> >> Your method is not the absolute best way either. There is no absolute
> >> best way.
>
> >> --
> >> Regards, Robert =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 =A0 =A0 =A0 =A0http://www.arumes.com
>
> > =A0 Do you have more to say about which way you set exposure and when?
> >I am genuinely interested in how you decide to set exposure. At this
> >point I actually use both, "expose to the right" and light meter, for
> >the "fine art" shots. I can't see a difference, I was just curious in
> >a CD versus vinyl sort of way.
>
> >Porte
>
> There IS NO ONE RIGHT WAY. Not even a cut 'n dried dozen right ways. Each
> and every photograph requires a unique way to expose it properly. No
> automated metering system in the world will ever get it right for you.
> Unless you are like most people, a point 'n shooter, wanting some tech-he=
ad
> in a computer lab trying to decide your exposures for you the rest of you=
r
> life. The metering recommendation designed and programmed by someone who'=
s
> never taken one photo in their life. Or even worse, if you depend on the
> advice of all those armchair photographers that infest the net and
> newsgroups. Those desperately pretending to be photographers, laughing to
> themselves when they find out they managed to convince someone to do as
> they told you to do, never having held even one camera in their own
> lifetime. And you all fall for it like the fools that you are.
>
> This is why I find a live-view display (EVF or LCD) so valuable today. I
> can instantly see that I have to lower the exposure of a sunrise or sunse=
t
> by as much as 2.5-3.0 EV stops to properly capture the intense colors and
> dramatic cloud contrasts. I can instantly see why I have to overexpose th=
e
> scene on the water by up to 1.5 EV steps or more and let all those
> highlights on the water go out completely. I can instantly see that in
> order to capture the moon's features while it's rising above that mountai=
n
> peak that I'll have to underexpose by 4 or more stops, ambient light
> depending.
>
> If you are depending on your metering system, depending on some lame-asse=
d
> one-size-fits-all amateur's recommendation of "always expose to the right=
",
> and all the other inane nonsense of theirs, it will only keep you glued t=
o
> your editor trying to desperately repair what you failed to do right in t=
he
> first place. Never getting it quite right in editing, ever, no matter wha=
t
> you do. RAW file or not. I shoot with RAW files and I NEVER use that lame
> beginner snapshooter's recommendation of "expose to the right".
>
> Photography (digital especially) may be greatly depending on science, but
> it is all art. 100% art. There's no one right color of oil-paints, no one
> right medium, no one right brush, no one right way to create a
> brush-stroke. ...
>
> Get your heads out of your collective tech-head's asses.

Is the live view a JPEG generated by the camera?

>> Porte
> For me, digital is the opposite of film in exposure emphasis.
> In film, you expose for the shadows, while in digital you should expose 
> for the highlights.
> You can't print underexposed shadows on a film negative but you can burn 
> in overexposed highlights since the negatives tend to hold some 
> information in that area.
> You can't print overexposed highlights in a digital image but you can 
> tease out information from underexposed shadows in digital processing.
> You can't treat your entire image the same way, so you need to apply 
> techniques similar to dodging and burning in the digital realm using area 
> adjustments of an image and the various tools/techniques available in 
> image editors.

Exactly!  The clipping that occurs in digital photography is rather harsh 
.... all scene details more luminous than the clipping (saturation of the 
sensor) point are gone, gone, gone.  You can't tease them out with any 
amount of post-processing, regardless of how heroic or exotic.  I fail to 
understand why such a basic concept is so hard to understand.

Film does not "clip" in the same manner and some folks just don't seem to 
get it.  There are curves with soft knees and then there are curves with 
very sharp knees.  They are very different (in terms of useful output) when 
the input data approaches and exceeds them.  A soft knee means that there is 
compression of the data and that means that a correction that employs 
decompression can restore the data, at least to some extent.

So, expose to the right if you can afford lost high-lites ... and I do mean 
to emphasize LOST.  Like a hair-cut, clipped is gone. 

Charles wrote:

> 
> So, expose to the right if you can afford lost high-lites ... and I do mean 
> to emphasize LOST.  Like a hair-cut, clipped is gone. 
> 
> 

The point is to expose to the right if you can't afford to lose
low light detail, just be careful to avoid sensor overload
where you don't want it.

It works just fine, unless you are an idiot
P&S troll that just wants to depend on P&S to do his
job.

Doug McDonald

"Charles" <charlesschuler@comcast.net> wrote:
>>> Porte
>> For me, digital is the opposite of film in exposure emphasis.
>> In film, you expose for the shadows, while in digital you should expose
>> for the highlights.

Actually, since film is a negative, the two are in fact
actually the same.  Expose for the brightest range of the
*recording* *mechanism*.

That just happens to be the dark areas of a scene with
film (where the negative is clear) and the bright areas
of a scene with an electronic sensor (the highest
voltage output).

>> You can't print underexposed shadows on a film negative but you can burn
>> in overexposed highlights since the negatives tend to hold some
>> information in that area.
>>
>> You can't print overexposed highlights in a digital image but you can
>> tease out information from underexposed shadows in digital processing.
>> You can't treat your entire image the same way, so you need to apply
>> techniques similar to dodging and burning in the digital realm using area
>> adjustments of an image and the various tools/techniques available in
>> image editors.
>
>Exactly!  The clipping that occurs in digital photography is rather harsh
>... all scene details more luminous than the clipping (saturation of the
>sensor) point are gone, gone, gone.  You can't tease them out with any
>amount of post-processing, regardless of how heroic or exotic.  I fail to
>understand why such a basic concept is so hard to understand.

Digital clipping is almost never "saturation of the
sensor".  Unless you are shooting at the base ISO
clipping is saturation of the Analog-Digital-Converter
(ADC) by sensor output that is greater than the maximum
ADC input.

>Film does not "clip" in the same manner and some folks just don't seem to
>get it.  There are curves with soft knees and then there are curves with
>very sharp knees.  They are very different (in terms of useful output) when
>the input data approaches and exceeds them.  A soft knee means that there is
>compression of the data and that means that a correction that employs
>decompression can restore the data, at least to some extent.

That is easy enough to do with digital too, though
obviously "expose to the right" does not do it.  And it
should be noted that technically such a compression
curve adds a "noise" to the image!  People get all
excited about digital "noise", but rarely understand
what it is, or that such things as the supposed
"latitude" of film constitutes a significant addition of
noise to an image.  (Technically it is a "distortion".)

>So, expose to the right if you can afford lost high-lites ... and I do mean
>to emphasize LOST.  Like a hair-cut, clipped is gone.

False.

If you apply the philosophy of "expose to the right"
there will be no loss of highlights, unless of course
you *want* to blow some of them away.  And that is
commonly the exact desire for such things a light
sources, reflections, etc.

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

Porte Rouge wrote:
> Al Dykes wrote:
>> John A. wrote:
>>> Porte Rouge wrote:
>>
>>>> I set my exposure to slide the histogram to the right, without clipping
>>>> ( when I have time), to capture the most tonal levels . So, now when I
>>>> am editing the photos they are over exposed(not clipped). A sunrise is
>>>> a good example. The deep colors are washed out. The obvious fix(to me
>>>> anyway) in Lightroom or CS4 is to reduce the exposure. Now my question
>>>> is, by reducing exposure in post, am I just ending up in the same place
>>>> (histogram to the left) as if I had just ignored the histogram when I
>>>> was shooting and set the exposure to properly expose the image using
>>>> my light meter? I guess in short I am asking if Lightroom or CS4 loses
>>>> tonal values when you reduce exposure in editing.
>>>  
>>> You overexpose short of clipping, the apply a likewise (if preferred)
>>> reverse adjustment in post. This is to maximize the signal-to-noise
>>> and tonal gradations in the exposure.
>>> The tonal aspect is analogous to setting a digital multimeter to the
>>> proper scale before taking a reading, in order to maximize the
>>> significant digits.
>>
>> This blog article talks about making the best of exposing to the
>> right.
>>
>> http://www.luminous-landscape.com/tutorials/right-hista.shtml
> 
>    Wow, good stuff. I had to run out and get my camera and check the
> settings. I don't understand what he says about the white balance. I
> have it set on auto and have ignored it when shooting RAW. Should I
> adjust it for each lighting condition when I shoot and this will give
> me a truer histogram?

WB can effect the histogram a lot if you make wild adjustments but auto 
is usually close enough to not matter much I'd guess.

-- 
Paul Furman
www.edgehill.net
www.baynatives.com

all google groups messages filtered due to spam

Paul Furman <paul-@-edgehill.net> wrote:
>Porte Rouge wrote:
>> Al Dykes wrote:
>>> John A. wrote:
>>>
>>> This blog article talks about making the best of exposing to the
>>> right.
>>>
>>> http://www.luminous-landscape.com/tutorials/right-hista.shtml
>>    Wow, good stuff. I had to run out and get my camera
>> and check the
>> settings. I don't understand what he says about the white balance. I
>> have it set on auto and have ignored it when shooting RAW. Should I
>> adjust it for each lighting condition when I shoot and this will give
>> me a truer histogram?
>
>WB can effect the histogram a lot if you make wild adjustments but auto
>is usually close enough to not matter much I'd guess.

Sort of depends on how close is "enough".  But auto
isn't any different than a wild guess as far as the
histogram goes!

The basic problem is that the sensor has twice as many
green sensors as red or blue sensors, and thus a
"correct" histogram should take that into account, but
doesn't.  If WB actually is adjusted to make the
histogram more correct, the JPEG image produced (and
displayed by the camera) will be quite greenish, and not
exactly appealing.  (Which means you don't want to show
it to anyone, and have to wait until after the RAW data
is post processed to let anybody see it.)

What is gained, however, is probably not of great
advantage.  All you really need to know is that the
right edge of the histogram (and the point at which a
highlight display starts to blink) is probably about 1/2
to 3/4 of an fstop below maximum exposure.  Take your
pick...  set exposure to where the brightest highlight
just barely blinks, and you lose just under 1 fstop of
dynamic range, but gain exactly that much "latitude" for
over exposed highlights.  Or set the exposure about 1/2
to 3/4 an fstop past where the brightest highlight
blinks to get maximum dynamic range (and no latitude).

But regardless of that, the cited URL above from
luminous-landscape is *not* full of good stuff.  They
miss the point entirely, and provide nothing that is
actually useful!  All that changing in-camera contrast
does is compress/uncompress the histograms idea of
middle gray.  It does not change where the highlights
fall, and thus does not change what you would set for
the exposure.  (Does anyone ever look at the shape of an
in-camera histogram and make adjustments as a result?
It's a meaningless excercise, which will not change the
camera raw data.  The shape of a post processing
histogram is very useful, but not an in-camera
histogram.)

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

Floyd L. Davidson wrote:

> But regardless of that, the cited URL above from
> luminous-landscape is *not* full of good stuff.  They
> miss the point entirely, and provide nothing that is
> actually useful!  All that changing in-camera contrast
> does is compress/uncompress the histograms idea of
> middle gray.  It does not change where the highlights
> fall, and thus does not change what you would set for
> the exposure.  (Does anyone ever look at the shape of an
> in-camera histogram and make adjustments as a result?
> It's a meaningless excercise, which will not change the
> camera raw data.  The shape of a post processing
> histogram is very useful, but not an in-camera
> histogram.)
> 

What you say is wrong for the Canon 30D. The histogram does
not change the raw data stored by the camera. But the camera setting DOES
change the camera displayed histogram. IF you set the camera "comtrast"
setting high, the highlights in the histogram get pushed way up
and are indeed useless for setting exposure. Ii you set it low,
at -3 or -4, the histogram displayed by the camera agrees quite nicely
with how close you are getting to clipping. At -4 the blinking clip display,
the histogram, and the raw file all agree well about how close you are
to clipping.

And yes, I do look at the in-camera histogram. It works.

Doug McDonald

Doug McDonald <mcdonald@NoSpAmscs.uiuc.edu> wrote:
>Floyd L. Davidson wrote:
>
>> But regardless of that, the cited URL above from
>> luminous-landscape is *not* full of good stuff.  They
>> miss the point entirely, and provide nothing that is
>> actually useful!  All that changing in-camera contrast
>> does is compress/uncompress the histograms idea of
>> middle gray.  It does not change where the highlights
>> fall, and thus does not change what you would set for
>> the exposure.  (Does anyone ever look at the shape of an
>> in-camera histogram and make adjustments as a result?
>> It's a meaningless excercise, which will not change the
>> camera raw data.  The shape of a post processing
>> histogram is very useful, but not an in-camera
>> histogram.)
>>
>
>What you say is wrong for the Canon 30D.  The histogram does
>not change the raw data stored by the camera. But the camera setting DOES
>change the camera displayed histogram. IF you set the camera "comtrast"
>setting high, the highlights in the histogram get pushed way up
>and are indeed useless for setting exposure. Ii you set it low,
>at -3 or -4, the histogram displayed by the camera agrees quite nicely
>with how close you are getting to clipping.

The brightest part will still show at *exactly* the same
place.  If you set exposure so that the brightest part
of the histogram is just barely less than the right edge
of the graph, it will be the same regardless of how
in-camera contrast is set.  What contrast will change is
how much of the area of the graph is spread out over the
entire graph (low contrast) as opposed to being peaked
in some portion of the graph (high contrast).

Changing the contrast does *not* change the value of the
brightest part of the image, which is what you use to set
exposure by the "expose to the right" method.

>At -4 the blinking clip display,
>the histogram, and the raw file all agree well about how close you are
>to clipping.

If you want to see a good demonstration of how it works,
set your camera to maximum contrast, use manual
exposure, and take a picture of an indoor light fixture.
It will be dramatic if the area around the light fixture
is relatively white and there is little light from any
source other than the fixture.  Zoom in or be at a
distance where the light fixture is a significant part
of the image area, but most of it is the area around the
light and thus darker.

Look at the histogram, and experiment with exposure.
The idea is to find the exact exposure where the
histogram bumps the right side of the chart.  More
exposure will cause a spike to climb up the right side,
less exposure will cause gap to form between the graph
and the right side.  Perhaps the ideal exposure for this
experiment is where there is just a small spike, because it
will be easiest to compare the height of the spike to see
if exposure changes.

Once you have that, adjust the in-camera contrast
setting from maximum to minimum, and check the histogram
for each exposure.  What you'll find is that the little
spike at the right side doesn't change.  What does
change is the spread of the less bright areas of the
image.  If you shoot a bare bulb and have a dark
background the entire bulk of the graph will be over on
the left side.  It will be wider with lower contrast and
narrower for high contrast.  The amount of area will
depend on how closely you zoom in on the light fixture
(the ratio of light source to background), and the
spread that it has along the right side of the histogram
will depend on the difference in brightness of the light
and the background.

Adjust the physical attributes to get a useful
histogram.  Then change the contrast setting to see what
it actually does affect.

>And yes, I do look at the in-camera histogram. It works.

But what do you look for?  Not the distribution of the
area under the graph!  That's what the contrast setting
will change.  It does not change the highest value of
the displayed graph though (which exposure does change).

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

On Mon, 05 Oct 2009 21:18:08 -0500, Doug McDonald
<mcdonald@NoSpAmscs.uiuc.edu> wrote:

>Floyd L. Davidson wrote:
>
>> But regardless of that, the cited URL above from
>> luminous-landscape is *not* full of good stuff.  They
>> miss the point entirely, and provide nothing that is
>> actually useful!  All that changing in-camera contrast
>> does is compress/uncompress the histograms idea of
>> middle gray.  It does not change where the highlights
>> fall, and thus does not change what you would set for
>> the exposure.  (Does anyone ever look at the shape of an
>> in-camera histogram and make adjustments as a result?
>> It's a meaningless excercise, which will not change the
>> camera raw data.  The shape of a post processing
>> histogram is very useful, but not an in-camera
>> histogram.)
>> 
>
>What you say is wrong for the Canon 30D. The histogram does
>not change the raw data stored by the camera. But the camera setting DOES
>change the camera displayed histogram. IF you set the camera "comtrast"
>setting high, the highlights in the histogram get pushed way up
>and are indeed useless for setting exposure. Ii you set it low,
>at -3 or -4, the histogram displayed by the camera agrees quite nicely
>with how close you are getting to clipping. At -4 the blinking clip display,
>the histogram, and the raw file all agree well about how close you are
>to clipping.
>
>And yes, I do look at the in-camera histogram. It works.
>
>Doug McDonald

If you had a CHDK capable camera, you could use any of the various
live-view RGB color histograms to find out which of any color channels need
to have their contrast reduced too.  I found that an overall -2 on contrast
on the "custom color" settings along with a -2 setting on the R channel of
Canon cameras gives a more accurate rendition, provides maximum dynamic
range, and doesn't clip the R channel first on highlights. I could reduce B
and G by a -2 also for even more dynamic range, but then I'd lose out the
nice balance. And, quite frankly, it already has more dynamic range than
any film I used to use, so it's not all that important. Few if any
interesting and well composed shots will benefit from more dynamic range. A
large dynamic range is the crutch of snapshooters that don't know how to
properly expose a subject in the first place and will then always try to
depend on post-processing to fix all their beginner's errors.

On Mon, 05 Oct 2009 17:58:51 -0800, floyd@apaflo.com (Floyd L.
Davidson) wrote:

>Paul Furman <paul-@-edgehill.net> wrote:
>>Porte Rouge wrote:
>>> Al Dykes wrote:
>>>> John A. wrote:
>>>>
>>>> This blog article talks about making the best of exposing to the
>>>> right.
>>>>
>>>> http://www.luminous-landscape.com/tutorials/right-hista.shtml
>>>    Wow, good stuff. I had to run out and get my camera
>>> and check the
>>> settings. I don't understand what he says about the white balance. I
>>> have it set on auto and have ignored it when shooting RAW. Should I
>>> adjust it for each lighting condition when I shoot and this will give
>>> me a truer histogram?
>>
>>WB can effect the histogram a lot if you make wild adjustments but auto
>>is usually close enough to not matter much I'd guess.
>
>Sort of depends on how close is "enough".  But auto
>isn't any different than a wild guess as far as the
>histogram goes!
>
>The basic problem is that the sensor has twice as many
>green sensors as red or blue sensors, and thus a
>"correct" histogram should take that into account, but
>doesn't.  If WB actually is adjusted to make the
>histogram more correct, the JPEG image produced (and
>displayed by the camera) will be quite greenish, and not
>exactly appealing.  (Which means you don't want to show
>it to anyone, and have to wait until after the RAW data
>is post processed to let anybody see it.)
>
>What is gained, however, is probably not of great
>advantage.  All you really need to know is that the
>right edge of the histogram (and the point at which a
>highlight display starts to blink) is probably about 1/2
>to 3/4 of an fstop below maximum exposure.  Take your
>pick...  set exposure to where the brightest highlight
>just barely blinks, and you lose just under 1 fstop of
>dynamic range, but gain exactly that much "latitude" for
>over exposed highlights.  Or set the exposure about 1/2
>to 3/4 an fstop past where the brightest highlight
>blinks to get maximum dynamic range (and no latitude).
>
>But regardless of that, the cited URL above from
>luminous-landscape is *not* full of good stuff.  They
>miss the point entirely, and provide nothing that is
>actually useful!  All that changing in-camera contrast
>does is compress/uncompress the histograms idea of
>middle gray.  It does not change where the highlights
>fall, and thus does not change what you would set for
>the exposure.  (Does anyone ever look at the shape of an
>in-camera histogram and make adjustments as a result?

I do, and I expect many others would also.

I take it from this question you do not do this and take your
exposures as you find them.

>It's a meaningless excercise, which will not change the
>camera raw data.  The shape of a post processing
>histogram is very useful, but not an in-camera
>histogram.)

With respect, you are wrong. The in-camera histogram will help you
adjust your exposure if the first one is not right.



Eric Stevens

On 10/5/09 16:44 , Charles wrote:
>>> Porte
>> For me, digital is the opposite of film in exposure emphasis.
>> In film, you expose for the shadows, while in digital you should expose
>> for the highlights.
>> You can't print underexposed shadows on a film negative but you can burn
>> in overexposed highlights since the negatives tend to hold some
>> information in that area.
>> You can't print overexposed highlights in a digital image but you can
>> tease out information from underexposed shadows in digital processing.
>> You can't treat your entire image the same way, so you need to apply
>> techniques similar to dodging and burning in the digital realm using area
>> adjustments of an image and the various tools/techniques available in
>> image editors.
>
> Exactly!  The clipping that occurs in digital photography is rather harsh
> ... all scene details more luminous than the clipping (saturation of the
> sensor) point are gone, gone, gone.  You can't tease them out with any
> amount of post-processing, regardless of how heroic or exotic.  I fail to
> understand why such a basic concept is so hard to understand.
>

   You've answered your own questions, here.


> Film does not "clip" in the same manner and some folks just don't seem to
> get it.  There are curves with soft knees and then there are curves with
> very sharp knees.  They are very different (in terms of useful output) when
> the input data approaches and exceeds them.  A soft knee means that there is
> compression of the data and that means that a correction that employs
> decompression can restore the data, at least to some extent.
>
> So, expose to the right if you can afford lost high-lites ... and I do mean
> to emphasize LOST.  Like a hair-cut, clipped is gone.
>

   Not all highlights contain details. These can be lost. That 
reflection in a Packard's bumper on a bright, sunny day is just a 
bright spot. Expose to retain that detail and you'll be looking at 
the kind of night shot done by Hollywood in the days of "Yancy 
Derringer."

   Accept that those specular reflections contains no detail, and 
you can easily expose more 'to the right' without any loss of image 
detail, while recovering more low light detail with lower noise.

   Dynamic range compression with film was a limitation that 
shooters learned to work around, embrace, or simply accept. And like 
tape hiss in analog audio, it covered a multitude of sins.

   The linear nature of digital is no different. It's a limitation 
that requires practical evasions. You either learn to work with it, 
or not. And the output reflects your choice.

Eric Stevens <eric.stevens@sum.co.nz> wrote:
>On Mon, 05 Oct 2009 17:58:51 -0800, floyd@apaflo.com (Floyd L.
>Davidson) wrote:
>>But regardless of that, the cited URL above from
>>luminous-landscape is *not* full of good stuff.  They
>>miss the point entirely, and provide nothing that is
>>actually useful!  All that changing in-camera contrast
>>does is compress/uncompress the histograms idea of
>>middle gray.  It does not change where the highlights
>>fall, and thus does not change what you would set for
>>the exposure.  (Does anyone ever look at the shape of an
>>in-camera histogram and make adjustments as a result?
>
>I do, and I expect many others would also.
>
>I take it from this question you do not do this and take your
>exposures as you find them.

As I noted, the *shape* of the curve has absolutely
nothing to do with setting exposure.

If you check the shape, what you learn is the tonal
distribution within the recorded dynamic range, not the
range itself.  The histogram shape, and thus the
in-camera contrast setting, is useless and has no effect
at all on the camera raw data that is later manipulated
with post processing.

>>It's a meaningless excercise, which will not change the
>>camera raw data.  The shape of a post processing
>>histogram is very useful, but not an in-camera
>>histogram.)
>
>With respect, you are wrong. The in-camera histogram will help you
>adjust your exposure if the first one is not right.

You need to learn to read a little better Steven.

The histogram will help you adjust your exposure, and
that is *exactly* what I have said.  What I've also said
is that changing the in-camera contrast setting does not
change the histogram in any way that will affect
exposure.  It does *not* change how close the graph approaches
the right side.  All it does is change the distribution
of the graph outward from the left side.

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

Floyd L. Davidson wrote:
> Doug McDonald <mcdonald@NoSpAmscs.uiuc.edu> wrote:
>> Floyd L. Davidson wrote:
>>
>>> But regardless of that, the cited URL above from
>>> luminous-landscape is *not* full of good stuff.  They
>>> miss the point entirely, and provide nothing that is
>>> actually useful!  All that changing in-camera contrast
>>> does is compress/uncompress the histograms idea of
>>> middle gray.  It does not change where the highlights
>>> fall, and thus does not change what you would set for
>>> the exposure.  (Does anyone ever look at the shape of an
>>> in-camera histogram and make adjustments as a result?
>>> It's a meaningless excercise, which will not change the
>>> camera raw data.  The shape of a post processing
>>> histogram is very useful, but not an in-camera
>>> histogram.)
>>>
>> What you say is wrong for the Canon 30D.  The histogram does
>> not change the raw data stored by the camera. But the camera setting DOES
>> change the camera displayed histogram. IF you set the camera "comtrast"
>> setting high, the highlights in the histogram get pushed way up
>> and are indeed useless for setting exposure. Ii you set it low,
>> at -3 or -4, the histogram displayed by the camera agrees quite nicely
>> with how close you are getting to clipping.
> 
> The brightest part will still show at *exactly* the same
> place. 

Maybe for contrast (though I doubt it) but WB makes a big difference. I 
just tested at 25K & 100K, the highlights are completely different. I'm 
looking at split RGB histograms btw.


> If you set exposure so that the brightest part
> of the histogram is just barely less than the right edge
> of the graph, it will be the same regardless of how
> in-camera contrast is set.  What contrast will change is
> how much of the area of the graph is spread out over the
> entire graph (low contrast) as opposed to being peaked
> in some portion of the graph (high contrast).
> 
> Changing the contrast does *not* change the value of the
> brightest part of the image, which is what you use to set
> exposure by the "expose to the right" method.
> 
>> At -4 the blinking clip display,
>> the histogram, and the raw file all agree well about how close you are
>> to clipping.
> 
> If you want to see a good demonstration of how it works,
> set your camera to maximum contrast, use manual
> exposure, and take a picture of an indoor light fixture.
> It will be dramatic if the area around the light fixture
> is relatively white and there is little light from any
> source other than the fixture.  Zoom in or be at a
> distance where the light fixture is a significant part
> of the image area, but most of it is the area around the
> light and thus darker.
> 
> Look at the histogram, and experiment with exposure.
> The idea is to find the exact exposure where the
> histogram bumps the right side of the chart.  More
> exposure will cause a spike to climb up the right side,
> less exposure will cause gap to form between the graph
> and the right side.  Perhaps the ideal exposure for this
> experiment is where there is just a small spike, because it
> will be easiest to compare the height of the spike to see
> if exposure changes.
> 
> Once you have that, adjust the in-camera contrast
> setting from maximum to minimum, and check the histogram
> for each exposure.  What you'll find is that the little
> spike at the right side doesn't change.  What does
> change is the spread of the less bright areas of the
> image.  If you shoot a bare bulb and have a dark
> background the entire bulk of the graph will be over on
> the left side.  It will be wider with lower contrast and
> narrower for high contrast.  The amount of area will
> depend on how closely you zoom in on the light fixture
> (the ratio of light source to background), and the
> spread that it has along the right side of the histogram
> will depend on the difference in brightness of the light
> and the background.
> 
> Adjust the physical attributes to get a useful
> histogram.  Then change the contrast setting to see what
> it actually does affect.
> 
>> And yes, I do look at the in-camera histogram. It works.
> 
> But what do you look for?  Not the distribution of the
> area under the graph!  That's what the contrast setting
> will change.  It does not change the highest value of
> the displayed graph though (which exposure does change).
> 


-- 
Paul Furman
www.edgehill.net
www.baynatives.com

all google groups messages filtered due to spam

Floyd L. Davidson wrote:
>
> As I noted, the *shape* of the curve has absolutely
> nothing to do with setting exposure.
> 
> If you check the shape, what you learn is the tonal
> distribution within the recorded dynamic range, not the
> range itself. 

For the Canon 30D, that is incorrect. True, you do learn the shape.

But at contrast levels (as described in the camera setup)
of -3 or 0-, you **DO** learn at least the high end of the
contrast range. Do you understand this? That is, at -3 or -4,
there is enough detain in the in-camera histogram to tell,
quite accurately, how close you are to overload of the raw file.
At -2 or higher, the compression of the (internal) jpeg from which
the histogram is made makes telling that problematic.


> The histogram shape, and thus the
> in-camera contrast setting, is useless and has no effect
> at all on the camera raw data that is later manipulated
> with post processing.

At settings more than -3, that is true always, and yes,
it has no effect on the raw file.


> 
>>> It's a meaningless excercise, which will not change the
>>> camera raw data.  The shape of a post processing
>>> histogram is very useful, but not an in-camera
>>> histogram.)
>> With respect, you are wrong. The in-camera histogram will help you
>> adjust your exposure if the first one is not right.
> 
> You need to learn to read a little better Steven.
> 
> The histogram will help you adjust your exposure, and
> that is *exactly* what I have said.  What I've also said
> is that changing the in-camera contrast setting does not
> change the histogram in any way that will affect
> exposure.  It does *not* change how close the graph approaches
> the right side.  All it does is change the distribution
> of the graph outward from the left side.


THAT LAST PARAGRAPH IS INCORRECT FOR THE CANON 30D!

Changing the in-camera contrast setting DOES change how close
the graph approaches the right side. REALLY!! I've tried it many times.
Changing the in-camera contrast setting seems to expand or contract
the histogram about some point in the middle. I'm not saying its
the exact center, I have not tried telling. I could do this,
but have not.

Have YOU examined the histogram on a Canon 30D?

If you have not, I suggest that you preface your remarks
with "on the cameras I have actually personally tested i.e.
[list of cameras] ...".

Doug McDonald


> 

On Tue, 06 Oct 2009 00:52:09 -0800, floyd@apaflo.com (Floyd L.
Davidson) wrote:

>Eric Stevens <eric.stevens@sum.co.nz> wrote:
>>On Mon, 05 Oct 2009 17:58:51 -0800, floyd@apaflo.com (Floyd L.
>>Davidson) wrote:
>>>But regardless of that, the cited URL above from
>>>luminous-landscape is *not* full of good stuff.  They
>>>miss the point entirely, and provide nothing that is
>>>actually useful!  All that changing in-camera contrast
>>>does is compress/uncompress the histograms idea of
>>>middle gray.  It does not change where the highlights
>>>fall, and thus does not change what you would set for
>>>the exposure.  (Does anyone ever look at the shape of an
>>>in-camera histogram and make adjustments as a result?
>>
>>I do, and I expect many others would also.
>>
>>I take it from this question you do not do this and take your
>>exposures as you find them.
>
>As I noted, the *shape* of the curve has absolutely
>nothing to do with setting exposure.
>
>If you check the shape, what you learn is the tonal
>distribution within the recorded dynamic range, not the
>range itself.  The histogram shape, and thus the
>in-camera contrast setting, is useless and has no effect
>at all on the camera raw data that is later manipulated
>with post processing.
>
>>>It's a meaningless excercise, which will not change the
>>>camera raw data.  The shape of a post processing
>>>histogram is very useful, but not an in-camera
>>>histogram.)
>>
>>With respect, you are wrong. The in-camera histogram will help you
>>adjust your exposure if the first one is not right.
>
>You need to learn to read a little better Steven.
>
>The histogram will help you adjust your exposure, and
>that is *exactly* what I have said.  What I've also said
>is that changing the in-camera contrast setting does not
>change the histogram in any way that will affect
>exposure.  It does *not* change how close the graph approaches
>the right side.  All it does is change the distribution
>of the graph outward from the left side.

But not in the RAW data, surely? Are you talking shooting JPEGs - or
what kind of camera is it?



Eric Stevens

> Digital clipping is almost never "saturation of the
> sensor".  Unless you are shooting at the base ISO
> clipping is saturation of the Analog-Digital-Converter
> (ADC) by sensor output that is greater than the maximum
> ADC input.

And what difference would that make?  There is no sharper knee than one 
imposed by basic mathematics.  2^8 = 256, is a simple example.  With 8 bits, 
the maximum value is 255, base 10, with NO exceptions possible.  You 
actually help to make the case that over-exposed digital shots guarantee 
lost information in the bright portions of the scene.

I continue to believe that exposing to the right is perpetuated by folks 
with limited experience and knowledge.  They are perhaps into the dark parts 
of scenes and don't understand dynamic range.  Many of us are more greedy 
and want details at both ends of the luminosity range.

Hey, blow those high-lites out!  If that is the intended message of a given 
scene, go for it.  I don't care for over-exposed shots ... they are just not 
my thing.  I have seen some high-key shots that were attractive and 
effective and do appreciate the skill and art of the photographers who can 
pull that off.

Specular high-lites might deserve to be blown out.  Not the point of my 
response.  I'll just say it one more time and then go away ... if it is 
clipped (by a sharp knee response curve ... due to sensor saturation or A/D 
saturation or any saturation link in the chain) it is GONE! 

In article <hadpc1$8up$1@news.eternal-september.org>, 
charlesschuler@comcast.net says...
> 
> So, expose to the right if you can afford lost high-lites ... and I do mean 
> to emphasize LOST.  Like a hair-cut, clipped is gone. 
> 
But unlike a hair-cut it never grows back. More of an amputation 
methinks...

Mike

On Tue, 6 Oct 2009 18:27:10 -0400, "Charles"
<charlesschuler@comcast.net> wrote:

>
>
>> Digital clipping is almost never "saturation of the
>> sensor".  Unless you are shooting at the base ISO
>> clipping is saturation of the Analog-Digital-Converter
>> (ADC) by sensor output that is greater than the maximum
>> ADC input.
>
>And what difference would that make?  There is no sharper knee than one 
>imposed by basic mathematics.  2^8 = 256, is a simple example.  With 8 bits, 
>the maximum value is 255, base 10, with NO exceptions possible.  You 
>actually help to make the case that over-exposed digital shots guarantee 
>lost information in the bright portions of the scene.
>
>I continue to believe that exposing to the right is perpetuated by folks 
>with limited experience and knowledge.  They are perhaps into the dark parts 
>of scenes and don't understand dynamic range.  Many of us are more greedy 
>and want details at both ends of the luminosity range.
>
>Hey, blow those high-lites out!  If that is the intended message of a given 
>scene, go for it.  I don't care for over-exposed shots ... they are just not 
>my thing.  I have seen some high-key shots that were attractive and 
>effective and do appreciate the skill and art of the photographers who can 
>pull that off.
>
>Specular high-lites might deserve to be blown out.  Not the point of my 
>response.  I'll just say it one more time and then go away ... if it is 
>clipped (by a sharp knee response curve ... due to sensor saturation or A/D 
>saturation or any saturation link in the chain) it is GONE! 

The "expose to the right" approach isn't about blowing highlights, or
otherwise pegging the sensors. It's about not leaving too big a gap on
the right side of the histogram so that the quantified & digitized
brightness readings cover a larger range from min to max. That's where
your dynamic range comes from in a digital camera. Perhaps it would be
clarifying to realize that digital light sensors read light linearly,
not on a curve, and at discrete levels. Also, white balance
adjustments are channel multipliers, not curves.

Don't like "overexposed" images? Counteradjust the exposure in post.
That's the second half of the technique anyway. It's easy, and you'll
find that at a given ISO you'll end up with less noise in the final
image.

Paul Furman <paul-@-edgehill.net> wrote:
>Floyd L. Davidson wrote:
>> Doug McDonald <mcdonald@NoSpAmscs.uiuc.edu> wrote:
>>> Floyd L. Davidson wrote:
>>>
>>>> But regardless of that, the cited URL above from
>>>> luminous-landscape is *not* full of good stuff.  They
>>>> miss the point entirely, and provide nothing that is
>>>> actually useful!  All that changing in-camera contrast
>>>> does is compress/uncompress the histograms idea of
>>>> middle gray.  It does not change where the highlights
>>>> fall, and thus does not change what you would set for
>>>> the exposure.  (Does anyone ever look at the shape of an
>>>> in-camera histogram and make adjustments as a result?
>>>> It's a meaningless excercise, which will not change the
>>>> camera raw data.  The shape of a post processing
>>>> histogram is very useful, but not an in-camera
>>>> histogram.)
>>>>
>>> What you say is wrong for the Canon 30D.  The histogram does
>>> not change the raw data stored by the camera. But the camera setting DOES
>>> change the camera displayed histogram. IF you set the camera "comtrast"
>>> setting high, the highlights in the histogram get pushed way up
>>> and are indeed useless for setting exposure. Ii you set it low,
>>> at -3 or -4, the histogram displayed by the camera agrees quite nicely
>>> with how close you are getting to clipping.
>> The brightest part will still show at *exactly* the
>> same
>> place.
>
>Maybe for contrast (though I doubt it) but WB makes a big difference. I
>just tested at 25K & 100K, the highlights are completely different. I'm
>looking at split RGB histograms btw.

That is exactly the point I *am* making.  WB changes the
histogram in a useful way.  The Luminous-Landscape
article did not talk about WB at all.  They discussed
changing the camera's setting for contrast, and that
simply does *nothing* useful for the histogram/exposure
issue.

And if you doubt that the contrast setting will not change
the histogram as stated, *try* *it*.  I gave an step by
step description of a very easy way to show exactly what
does and does not happen.  Why argue from supposition when
you could actually learn something about photography...

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

Charles wrote:
>
> 
> I continue to believe that exposing to the right is perpetuated by folks 
> with limited experience and knowledge.  They are perhaps into the dark parts 
> of scenes and don't understand dynamic range.  Many of us are more greedy 
> and want details at both ends of the luminosity range.
> 
> Hey, blow those high-lites out!  If that is the intended message of a given 
> scene, go for it.  I don't care for over-exposed shots ... they are just not 
> my thing.  I have seen some high-key shots that were attractive and 
> effective and do appreciate the skill and art of the photographers who can 
> pull that off.
> 
> Specular high-lites might deserve to be blown out.  Not the point of my 
> response.  I'll just say it one more time and then go away ... if it is 
> clipped (by a sharp knee response curve ... due to sensor saturation or A/D 
> saturation or any saturation link in the chain) it is GONE! 
> 


Again, you simply don't understand.

Let me explain. Say you are doing a landscape of a very
cloudy scene, with not a trace of sun visible, with high
level clouds blocking the sun, so it does not shine on lower
level clouds. The contrast in the sky is still moderately
high. The low key lighting also makes contrast in the
land part of the scene low. The whole affair is low contrast.

If you expose by TTL light meter, normally, it will expose
so that the average of the scene is 18% gray. The highlights,
that is, the brightest clouds, will not be clipped, in fact
they will be well below that. So you expose to the right so that
the brightest clouds are just below clipping. This gets more
photons, ergo, better S/N.

Now remove the high level clouds. The sun is shining on the
lower level clouds and is very, very, very bright. But the
foreground is in shade! You want to not clip the clouds.
The TTL meter will likely want to clip them. So you
are careful and expose to the right to avoid clipping the
clouds.

Now a little bit of sun shines of the foreground, on
a waterfall. If you use the same exposure as the paragraph
above, the specular highlights on the water will clip.
You may very well actually WANT that to happen, so you
are careful to let it.


You ALWAYS want to expose to the right, given enough light that
you don't need a too-long exposure and blurring. Indeed,
of course, you may want to clip specular highlights.

The idea is that this is the correct way, the photographer
simply has to understand how to get it right.

The only time you don't want to expose to the right is
if you are already at ISO 1600 or 3200 and still there
is too little light to avoid blurring if you do.

Doug McDonald

Keys to Happiness

Happiness is the only goal on earth that all people without exception
are seeking to attain. Believers and unbelievers alike seek to be
happy, but each party is using different methods.

However, only believers can achieve genuine happiness. All forms of
happiness attained without a firm belief in God, the Almighty, are
mere illusions.

The following are tips for the attainment of happiness:

1. Know that if you do not live within the scope of today, your
thoughts will be scattered, your affairs will become confused, and
your anxiety will increase. These realities are explained in the
following hadith:

=93When you are in the evening, do not expect to see themorning, and
when you are in the morning, do not expect to see the
evening.=94 (Saheeh Al-Bukhari)

2. Forget the past and all that it contained, focus on the present.

3. Do not completely preoccupy yourself with the future and then
discard the present. Be balanced in life, prepare yourself adequately
for all situations.

4. Do not be shaken by criticism; instead, be firm. Be sure that in
proportion to your worth, the level of people's criticism rises. Also,
make good use of criticism in discovering your shortcomings and
faults, and let it drive you toward self-improvement.

5. Have complete faith in God and perform good deeds; these are the
ingredients that makeup a good and happy life.

6. If you desire peace, tranquility, and comfort, you can find it all
in the remembrance of God.

7. You should know with certainty that everything that happens, occurs
in accordance with the divine decree.

8. Do not expect gratitude from anyone.

9. Train yourself to be prepared for the worst possibility.

10. Perhaps what has happened is in your best interest, even though
you may not comprehend how that can be so.

11. Everything that is decreed for the believer is the best for him.

12. Enumerate the blessings of God and be thankful for them.

13. Remember that you are better off than many others.

14. Relief comes from one hour to the next. Indeed, with each
difficulty there is relief.

15. In both times of hardship and ease, one should turn to
supplication and prayer, either patiently contented or thankful.

16. Calamities should strengthen your heart and reshape your outlook
in a positive way.

17. Do not let trivialities be the cause of your destruction.

18. Always remember that your God is Oft-Forgiving.

19. Assume an easy-going attitude and avoid anger.

20. Life is bread, water, and shade; so do not be perturbed by a lack
of any other material thing.

=93And in the heaven is your providence and that which you are
promised.=94 (Quran 51:22)

21. A daunting evil that seemingly will happen usually never occurs.

22. Look at those who have more afflictions and be grateful that you
have less.

23. Bear in mind the fact that God loves those who endure trials with
steadfastness, so seek to be one of them.

24. Constantly repeat those supplications that the Prophet (may God
praise him) taught us to say during times of hardship.

25. Work hard at something that is productive, and cast off idleness.

26. Do not spread rumors and do not listen to them. If you hear a
rumor inadvertently, do not believe it.

27. Know that your malice and your striving to seek revenge are much
more harmful to your health than they are to your antagonist.

28. The hardships that befall you atone for your sins, if you endure
with patience.

Source::: www.islamreligion.com

Doug McDonald <mcdonald@scs.uiuc.edu.remove.invalid> wrote:
>Floyd L. Davidson wrote:
>>
>> As I noted, the *shape* of the curve has absolutely
>> nothing to do with setting exposure.
>> If you check the shape, what you learn is the tonal
>> distribution within the recorded dynamic range, not the
>> range itself.
>
>For the Canon 30D, that is incorrect. True, you do learn the shape.

Stop guessing, and actually try it in a way that is
definitive.  If you don't come up with the correct
answers, describe precisely what you did and we can work
out what is wrong with the technique or the analysis of
it.

>But at contrast levels (as described in the camera setup)
>of -3 or 0-, you **DO** learn at least the high end of the
>contrast range. Do you understand this? That is, at -3 or -4,
>there is enough detain in the in-camera histogram to tell,
>quite accurately, how close you are to overload of the raw file.
>At -2 or higher, the compression of the (internal) jpeg from which
>the histogram is made makes telling that problematic.

You are admitting that it *doesn't* change the exposure
level at all!

Yes, for some scenes it might (but cannot in others)
push more of the area under the graph towards to right
at the right most edge, but it will *not* change where
the brightest part of the graph is located in relation
to the right edge, which is the *only* point of any
significance for setting exposure.

Let's reiterate those two points:

  1) The *only* characteristic of the histogram that
     is significant for setting exposure is the location
     of the right edge of the graphed data in relationship
     to the absolute right edge of the graph.

  2) In-camera contrast adjustment does not change the
     location of the right most edge of the graphed data.

If you have difficulty seeing when the graph is at the
right edge, the "corrective action" is to learn how to
read the graph, not a camera adjustment!  Indeed,
pushing more of the area closer to the right makes it,
in common instances, *more* difficult!  What you want to
watch for is a spike at the right end, and then back off
until there is none.  That is actually *harder* to see
when there are higher data counts on the right side.  It
is very easy to see if the graphed data amounts to a one
pixel horizontal line approaching the right side.

The above assumes no part of the image should have blown
highlights...; in fact it is not uncommon to *want* some
areas to blow out, and in that case the histogram is
useless anyway!  Use a blinking highlight display
instead.  And again, contrast settings will not have
*any* effect at all on the blinking highlight display.
None!  (Even with a Canon 30D!  Assuming it has a
highlight display...)

>> The histogram shape, and thus the
>> in-camera contrast setting, is useless and has no effect
>> at all on the camera raw data that is later manipulated
>> with post processing.
>
>At settings more than -3, that is true always, and yes,
>it has no effect on the raw file.

At any settings, -3, -5, or +5...  It is useless in terms
of setting the exposure, because it does not affect the
raw data *or* the location of the histogram's right edge.

>>>> It's a meaningless excercise, which will not change the
>>>> camera raw data.  The shape of a post processing
>>>> histogram is very useful, but not an in-camera
>>>> histogram.)
>>> With respect, you are wrong. The in-camera histogram will help you
>>> adjust your exposure if the first one is not right.
>> You need to learn to read a little better Steven.
>> The histogram will help you adjust your exposure, and
>> that is *exactly* what I have said.  What I've also said
>> is that changing the in-camera contrast setting does not
>> change the histogram in any way that will affect
>> exposure.  It does *not* change how close the graph approaches
>> the right side.  All it does is change the distribution
>> of the graph outward from the left side.
>
>THAT LAST PARAGRAPH IS INCORRECT FOR THE CANON 30D!

Try it and see!

>Changing the in-camera contrast setting DOES change how close
>the graph approaches the right side. REALLY!! I've tried it many times.
>Changing the in-camera contrast setting seems to expand or contract
>the histogram about some point in the middle. I'm not saying its
>the exact center, I have not tried telling. I could do this,
>but have not.

I realize you have not done this.  If you did you might
have a better understanding of how it works.

It changes the area under the graph, exanding or
contracting it from the left side.  It does not change
the location of the right end of the data.  That is, it
does not move the right edge of the data horizontally.
It may move data from 1 stop left of the edge closer to
the edge, but the *edge* stays where it was.

All you have to do is experiment with a single point source
of light against a less well light background, and all of
this should become obvious.

>Have YOU examined the histogram on a Canon 30D?
>
>If you have not, I suggest that you preface your remarks
>with "on the cameras I have actually personally tested i.e.
>[list of cameras] ...".

It is obvious from your description that you have not
learned the fine points of reading a histogram (which is
typical of most photograhers, so do not take that as an
insult), and have not actually experimented with a 30D
or any other camera to learn what is actually happening.

Again, contrast both in theory and in the practical
application of theory to a digital camera, changes slope
of the curve, not the range it covers.

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

Floyd L. Davidson wrote:

> Let's reiterate those two points:
> 
>   1) The *only* characteristic of the histogram that
>      is significant for setting exposure is the location
>      of the right edge of the graphed data in relationship
>      to the absolute right edge of the graph.
> 
>   2) In-camera contrast adjustment does not change the
>      location of the right most edge of the graphed data.
> 
> If you have difficulty seeing when the graph is at the
> right edge, the "corrective action" is to learn how to
> read the graph, not a camera adjustment! 

You are simply wrong.

I HAVE ACTUALLY DONE THIS WITH MY CAMERA.

I HAVE ACTUALLY DONE THIS WITH MY CAMERA.

I took exactly the same picture with the contrast set
at -4 and it set at 0 (and in between). The camera was set
on manual, the f/number and time were the same.
Upon inspection in the computer, the raw files were the same.
Neither file was overexposed. The scene had a white card in it, no
specular anything.

Now lets see what I saw on the camera histogram. With the -4
contrast setting, the beak due to the white card is well away
from the right edge, and the right edge of the red channel
is (I'm looking right now!) is about 1mm from the right edge,
while the blue and green are farther to the left, at roughly 2 amd 3mm to the left.
One mm is about 6 pixels on the view screen.

Now, looking at th histogram with the 0 (higher) contrast setting
is different (REMEMBER ... I'm looking at it right now!). The central
part of the histogram is expanded, with the "node" point where it expands about
being 40% of the way from the left. The top and bottom parts are compressed.
The top part is so compressed that the red channel bumps into the right
edge of the histogram display area. There is a tiny space between the top
of the green and the right edge. The top of the blue is about 1 mm
from the edge.

Thus, using the 0 in-camera contrast setting I would have not seen the
gap between the red channel and the right of the histogram, and would have
thought it overexposed.

Got it?

NOTE: if you wish to continue, tell me the last four digits of your
Canon 30D serial number. Mine is 3965.

Doug McDonald

mike wrote:
> In article <hadpc1$8up$1@news.eternal-september.org>, 
> charlesschuler@comcast.net says...
>> So, expose to the right if you can afford lost high-lites ... and I do mean 
>> to emphasize LOST.  Like a hair-cut, clipped is gone. 
>>
> But unlike a hair-cut it never grows back. More of an amputation 
> methinks...

http://www.telegraph.co.uk/news/newstopics/howaboutthat/6266097/Pensioner-grows-new-skull.html

-just kidding but 'never say never' <g>

Floyd L. Davidson wrote:

> 
> It is obvious from your description that you have not
> learned the fine points of reading a histogram (which is
> typical of most photograhers, so do not take that as an
> insult), and have not actually experimented with a 30D
> or any other camera to learn what is actually happening.


Let me say it again: I have ... AND HAD BEFORE I EVER POSTED ...
actually tried it on my very own Canon 30D and I DO know the fine points
of reading a histogram on this camera.

You are wrong to insult me by suggesting otherwise.

Finally I will say this: **IF** the in-camera histogram had
say 32768 pixels actually visible in it (8 times more than
the camera's 12 bit ADC) the you would be right,
at least if I had a good magnifier on me. I would,
in those circumstances, still be able to see the
"daylight" between the top of the scrunched up histogram
at the contrast = 0 setting and the top of the screen.  But with the very
limited resolution it actually has (maybe 150 pixels),
what I said in the previous post is correct.

Let me say this once more: I have been doing this histogram peeping for
years, and to be useful the contrast setting really DOES have to be at
-4 or -3. This is experience with this very camera speaking.
I do LOTS of landscape shots at low ISO where I intend all the
cloud detail and all the shadow detail to be visible in the final print.
This requires getting the exposure EXACTLY right for best effect. I KNOW how
to use the histogram to do this. And I KNOW how not to do it (i.e.
setting contrast > -3 in the camera is a no-no.)

TRY IT!! In your very own Canon 30D.

Doug MCDonald

Porte Rouge <porterougeman@gmail.com> wrote in news:eaf6a46b-3ba3-4ba1-
9999-206c3d903904@d4g2000vbm.googlegroups.com:

> I set my exposure to slide the histogram to the right, without clipping
> ( when I have time), to capture the most tonal levels . So, now when I
> am editing the photos they are over exposed(not clipped). A sunrise is
> a good example. The deep colors are washed out. The obvious fix(to me
> anyway) in Lightroom or CS4 is to reduce the exposure. Now my question
> is, by reducing exposure in post, am I just ending up in the same place
> (histogram to the left) as if I had just ignored the histogram when I
> was shooting and set the exposure to properly expose the image using
> my light meter? I guess in short I am asking if Lightroom or CS4 loses
> tonal values when you reduce exposure in editing.

They're not really over-exposed, they have simply put your highlights on a 
tone curve which makes the colors look pale.

The whole point of you "exposing to the right" is to increase the signal-
to-noise ratio.  The "number of tones" explanation often given is 
incorrect.  All digital cameras have too much noise at all tones to be 
limited by numbers of tones, at least in the RAW data.  The number of tones 
in your output are unrelated to the number of tones in the RAW exposure; 
you do not lose all you've gained when the software darkens the image.

This discussion transcended any technical merit long ago, but here's my two
cents.  

For both Nikon and Canon the histogram is based on converted channel RGB
values, not raw sensor values.
http://www.brisk.org.uk/photog/histo5.html
-- 
Mike Russell - http://www.curvemeister.com

On Sun, 4 Oct 2009 17:25:57 -0700 (PDT), Porte Rouge wrote:

>    Wow, good stuff. I had to run out and get my camera and check the
> settings. I don't understand what he says about the white balance. I
> have it set on auto and have ignored it when shooting RAW. Should I
> adjust it for each lighting condition when I shoot and this will give
> me a truer histogram?

Setting a more correct white balance may give a more accurate histogram,
but this is relying too much a coarse measurement.  

When in doubt, give up another half stop or more past the point where the
"blinkies" stop, or bracket your exposure as insurance against blown
highlights.
-- 
Mike Russell - http://www.curvemeister.com

"Charles" <charlesschuler@comcast.net> wrote:
>> Digital clipping is almost never "saturation of the
>> sensor".  Unless you are shooting at the base ISO
>> clipping is saturation of the Analog-Digital-Converter
>> (ADC) by sensor output that is greater than the maximum
>> ADC input.
>
>And what difference would that make?

The statement was that digital clipping was due to
saturation of the sensor.  The fact is, it's not.

And note that if it were there would be a significantly
different set of characteristics to apply, the ADC does
saturate with the mathematical precision you note below,
while the analog electronic sensor does not.

>There is no sharper knee than one
>imposed by basic mathematics.  2^8 = 256, is a simple example.  With 8 bits,
>the maximum value is 255, base 10, with NO exceptions possible.  You
>actually help to make the case that over-exposed digital shots guarantee
>lost information in the bright portions of the scene.

Nobody with an ounce of understanding would deny that,
so why do you find it worth noting that I 'actually
help' make that case?  Of course I did!

>I continue to believe that exposing to the right is perpetuated by folks
>with limited experience and knowledge.  They are perhaps into the dark parts
>of scenes and don't understand dynamic range.  Many of us are more greedy
>and want details at both ends of the luminosity range.

You must not understand dynamic range then, given that
statement!  The entire concept of "Expost To The Right"
is based on maximizing captured dynamic range.  It is
*precisely* a way to get maximum "details at both ends".

>Hey, blow those high-lites out!  If that is the intended message of a given
>scene, go for it.  I don't care for over-exposed shots ... they are just not
>my thing.  I have seen some high-key shots that were attractive and
>effective and do appreciate the skill and art of the photographers who can
>pull that off.
>
>Specular high-lites might deserve to be blown out.  Not the point of my
>response.  I'll just say it one more time and then go away ... if it is
>clipped (by a sharp knee response curve ... due to sensor saturation or A/D
>saturation or any saturation link in the chain) it is GONE!

Gee whiz, that's like arguing that rocks are "hard".
And of course that is exactly why people use the Expose
To The Right method.

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

Doug McDonald <mcdonald@NoSpAmscs.uiuc.edu> wrote:
>Floyd L. Davidson wrote:
>
>> Let's reiterate those two points:
>>   1) The *only* characteristic of the histogram that
>>      is significant for setting exposure is the location
>>      of the right edge of the graphed data in relationship
>>      to the absolute right edge of the graph.
>>   2) In-camera contrast adjustment does not change the
>>      location of the right most edge of the graphed data.
>> If you have difficulty seeing when the graph is at the
>> right edge, the "corrective action" is to learn how to
>> read the graph, not a camera adjustment!
>
>You are simply wrong.
>
>I HAVE ACTUALLY DONE THIS WITH MY CAMERA.
>
>I HAVE ACTUALLY DONE THIS WITH MY CAMERA.
>
>I took exactly the same picture with the contrast set
>at -4 and it set at 0 (and in between). The camera was set
>on manual, the f/number and time were the same.
>Upon inspection in the computer, the raw files were the same.
>Neither file was overexposed. The scene had a white card in it, no
>specular anything.
>
>Now lets see what I saw on the camera histogram. With the -4
>contrast setting, the beak due to the white card is well away
>from the right edge, and the right edge of the red channel
>is (I'm looking right now!) is about 1mm from the right edge,
>while the blue and green are farther to the left, at roughly 2 amd 3mm to the left.
>One mm is about 6 pixels on the view screen.
>
>Now, looking at th histogram with the 0 (higher) contrast setting
>is different (REMEMBER ... I'm looking at it right now!). The central
>part of the histogram is expanded, with the "node" point where it expands about
>being 40% of the way from the left. The top and bottom parts are compressed.
>The top part is so compressed that the red channel bumps into the right
>edge of the histogram display area. There is a tiny space between the top
>of the green and the right edge. The top of the blue is about 1 mm
>from the edge.
>
>Thus, using the 0 in-camera contrast setting I would have not seen the
>gap between the red channel and the right of the histogram, and would have
>thought it overexposed.
>
>Got it?

I got that it you still haven't done anything to
determine what the distinction is.

Do the same thing, except bracket the exposure by 1/2
and fstop, so that you can see the differences.

How far does 1/2 an fstop move that red channel graph,
compared to the 1mm (6 pixel) change you have above?

Use *both* settings of contrast and you'll find that
either way, the *same* exposure is what will put the
peak of the histogram exactly on the right edge of the
graph.  Which is to say that it is no more or less accurate
with either contrast setting!  You get the exact same
exposure either way.

As I noted previously, you clearly have not learned the
fine points of reading a histogram, and when you say
that one condition above would be easier to miss than
another, it just demonstrates exactly that point.  Yes,
with one given scene you might be more likely, with just
a quick glance, to miss what is there than you would
with a different contrast setting.  But the converse is
also true, in that with some different scene it would be
the *other* contrast setting that makes is more/less
likely to see the precision.

The point was that the exposure you get by using the
histogram is *not* going to be any more or less
*accurate* due to changing the in-camera contrast
settings.

That is as opposed to changing the White Balance, which
in fact *will* change the exposure setting derived from
the histogram; and setting the WB in one particular way
will make result in more "accurate" exposures, which is
something not gained by chaning the contrast.

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

Mike Russell <groupsRE@MOVEcurvemeister.com> wrote:
>This discussion transcended any technical merit long ago, but here's my two
>cents.

That is not true.  The discussion is about whether or
not there is merit to setting an in-camera contrast
setting to get more a more accurate histogram derived
exposure.  A Luminous Landscape article said you would,
and people believe it.  It is not valid.

On the other hand, others want to know why, if the above
is not valid, it is claimed that changing the WB setting
does have that effect.

There *is* technical merit in learning how to adjust a
camera to get accurate exposure.

>For both Nikon and Canon the histogram is based on converted channel RGB
>values, not raw sensor values.

That is basically true of all DSLR's.  It has
"problems", but it works.  The idea that raw data could
be used is not likely to be valid, and while it sounds
good in simple terms, the complex histogram that would
result just would not be as useful!

What I would like to see is a separate interpolation of
the raw data to provide a histogram, as opposed to the
one used to provide the JPEG image for preview display.
I like both having a useful preview image (one that is
not a sickly green) *and* an accurate histogram (which
produces a green tinge if used for a JPEG too).

>http://www.brisk.org.uk/photog/histo5.html--
>Mike Russell - http://www.curvemeister.com

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

Floyd L. Davidson wrote:

> 
> I got that it you still haven't done anything to
> determine what the distinction is.
> 
> Do the same thing, except bracket the exposure by 1/2
> and fstop, so that you can see the differences.
> 
> How far does 1/2 an fstop move that red channel graph,
> compared to the 1mm (6 pixel) change you have above?

Quite a bit ... at contrast setting 0. I don't have my camera with
me right now, so I can;t comment wuantitatively.



> 
> Use *both* settings of contrast and you'll find that
> either way, the *same* exposure is what will put the
> peak of the histogram exactly on the right edge of the
> graph.  Which is to say that it is no more or less accurate
> with either contrast setting!  You get the exact same
> exposure either way.
> 
>

I will be extra-careful and actually try this before commenting.

I can't extrapolate from my previous tests, because a 1/3 stop
increase in exposure, will result in
clipping of the red channel, and at contrast setting -4
will move the red channel all the way to the top.. A 1/3 stop decrease (at contrast
setting -4) will move all three channels to the left a clearly
visible amount. However, I still make MY point an negate yours:

my point is that at contrast setting -4, I can see that there
is no clipping, whereas at contrast setting 0, I cannot see that ...
and in fact there is no clipping. This negates your point
without doing the "decrease exposure" test.

But I will do the decrease exposure test to see if, at
contrast level 0 (and I will try -2 also), it will move the
red channel away from the absolute right edge of the histogram.

But, still, with what I have said YIOU POINT IS NEGATED.

You keep saying I don't understand ... but I **DO**

READ WHAT I JUST SAID!!!

In a condition where there is NO CLIPPING a contrast setting
-4 histogram allows me to see that, while one of zero does not.
That's teh bottom line. Can;t you see this?

Now, when I do your test, reducing 1/2 stop, if I CAN
see that red does not clip, then you have made the point that
using contrast setting 0 is in fact only 1/2 stop WORSE for
getting the highest possible unclipped exposure than using
contrast setting 0.

BUT ... my point is made already.

LET ME REPEAT, TRY TO UNDERSTAND:


In a condition where there is NO CLIPPING a contrast setting
-4 histogram allows me to see that, while one of zero does not.


Doug MCDonald

Doug McDonald wrote:
> Floyd L. Davidson wrote:
> 
>>
>> I got that it you still haven't done anything to
>> determine what the distinction is.
>>
>> Do the same thing, except bracket the exposure by 1/2
>> and fstop, so that you can see the differences.
>>
>> How far does 1/2 an fstop move that red channel graph,
>> compared to the 1mm (6 pixel) change you have above?
> 
> Quite a bit ... at contrast setting 0. I don't have my camera with
> me right now, so I can;t comment wuantitatively.
> 
> 

one more thing: I told you the last four digits of my Canon 30D's
serial number.

If you want to have any standing in this little Usenet flamefest,
you should at least tell me the last four digits of YOUR
Canon 30D serial number. At least, the number for the one you try
it on!

Do you have access to a 30D to try it on? Have you done so?

Doug McDonald

John Sheehy wrote:
> Porte Rouge wrote  
> 
>> I set my exposure to slide the histogram to the right, without clipping
>> ( when I have time), to capture the most tonal levels . So, now when I
>> am editing the photos they are over exposed(not clipped). A sunrise is
>> a good example. The deep colors are washed out. The obvious fix(to me
>> anyway) in Lightroom or CS4 is to reduce the exposure. Now my question
>> is, by reducing exposure in post, am I just ending up in the same place
>> (histogram to the left) as if I had just ignored the histogram when I
>> was shooting and set the exposure to properly expose the image using
>> my light meter? I guess in short I am asking if Lightroom or CS4 loses
>> tonal values when you reduce exposure in editing.
> 
> They're not really over-exposed, they have simply put your highlights on a 
> tone curve which makes the colors look pale.
> 
> The whole point of you "exposing to the right" is to increase the signal-
> to-noise ratio.  The "number of tones" explanation often given is 
> incorrect.  All digital cameras have too much noise at all tones to be 
> limited by numbers of tones, at least in the RAW data.  The number of tones 
> in your output are unrelated to the number of tones in the RAW exposure; 
> you do not lose all you've gained when the software darkens the image.

OK, the noise is more the reason but posterizing can be a problem in 
dark areas... raising shadows in post for the deepest shadows, and in 
skies where the color pallet is very limited. Doesn't the noise level 
follow this same principle? Or is there an unrelated reason for the 
noise levels paralleling tone counts?

-- 
Paul Furman
www.edgehill.net
www.baynatives.com

all google groups messages filtered due to spam

Doug McDonald <mcdonald@scs.uiuc.edu.remove.invalid> wrote:
>Floyd L. Davidson wrote:
>
>> I got that it you still haven't done anything to
>> determine what the distinction is.
>> Do the same thing, except bracket the exposure by 1/2
>> and fstop, so that you can see the differences.
>> How far does 1/2 an fstop move that red channel graph,
>> compared to the 1mm (6 pixel) change you have above?
>
>Quite a bit ... at contrast setting 0. I don't have my camera with
>me right now, so I can;t comment wuantitatively.
>
>> Use *both* settings of contrast and you'll find that
>> either way, the *same* exposure is what will put the
>> peak of the histogram exactly on the right edge of the
>> graph.  Which is to say that it is no more or less accurate
>> with either contrast setting!  You get the exact same
>> exposure either way.
>>
>
>I will be extra-careful and actually try this before commenting.
>
>I can't extrapolate from my previous tests, because a 1/3 stop
>increase in exposure, will result in
>clipping of the red channel, and at contrast setting -4
>will move the red channel all the way to the top.. A 1/3 stop decrease (at contrast
>setting -4) will move all three channels to the left a clearly
>visible amount. However, I still make MY point an negate yours:

Exactly.  No matter what the constrast adjustment, a
change in exposure moves all three channels by the same
amount, until one clips.  Clipping happens with the same
channel and at the same exposure no matter what your
contrast setting is.

>my point is that at contrast setting -4, I can see that there
>is no clipping, whereas at contrast setting 0, I cannot see that ...
>and in fact there is no clipping. This negates your point
>without doing the "decrease exposure" test.

Okay, if that is true, try a scene with different
illumination.  Try looking at a high key scene, then try
looking at a low key scene.  If low contrast helps with
one, high contrast will help with the other!

The point is still the same, contrast settings do *not*
affect the exposure.  Your ability to read a histogram
accurately is not of concern, and is variable not only
with the contrast setting but also with the type of
illumination.

>But I will do the decrease exposure test to see if, at
>contrast level 0 (and I will try -2 also), it will move the
>red channel away from the absolute right edge of the histogram.

If it doesn't, you are over exposing.  And the point is
that at contrast setting of -4, -2 and 0 the proper
exposure is always going to be the same.

>But, still, with what I have said YIOU POINT IS NEGATED.

Not even close.

>You keep saying I don't understand ... but I **DO**
>
>READ WHAT I JUST SAID!!!

I have.

>In a condition where there is NO CLIPPING a contrast setting
>-4 histogram allows me to see that, while one of zero does not.
>That's teh bottom line. Can;t you see this?

Switch between high key lighting and low key lighting
and tell me that it low contrast is an improvement for
both! :-)

You still miss the point that the proper exposure with
high or low contrast settings is exactly the same.  If
you read the histogram carefully, it makes no difference
what the contrast setting is.  And high or low contrast
may have exactly the opposite effects on ease of reading
the histogram for different scenes.

The answer is *not* setting contrast to something low,
it's learning how to read a histogram with precision!

>Now, when I do your test, reducing 1/2 stop, if I CAN
>see that red does not clip, then you have made the point that
>using contrast setting 0 is in fact only 1/2 stop WORSE for
>getting the highest possible unclipped exposure than using
>contrast setting 0.

There should not be any change at all in where you get
correct exposure, *if* you read the histogram properly.
The contrast setting does *not* change the exposure at
which the maximum brightness hits the right side of the
graph!

What changing to low contrast will do is move more of
the data points closer to the right end of the graph,
and for a low key scene that may help to read the graph
while for an high key scene it might make it more
difficult (because you cannot see the spike when
clipping just begins, making perfect look identical to
half a stop over exposed).

>BUT ... my point is made already.

>LET ME REPEAT, TRY TO UNDERSTAND:
>
>In a condition where there is NO CLIPPING a contrast setting
>-4 histogram allows me to see that, while one of zero does not.

Clipping begins at exactly the same place, and it either
has a data point at that level, or it doesn't.  Your
point seems to be that you cannot closely examine a
histogram graph for appropriate detail.  (I'm no spring
chicken myself, and wear bifocal glasses; though I am
very near sighted and sometimes just take the glasses
off to closely examine something like a histogram chart.
Is it possible that your eyesight does not allow seeing
fine detail up close?)

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

Doug McDonald <mcdonald@scs.uiuc.edu.remove.invalid> wrote:
>Doug McDonald wrote:
>> Floyd L. Davidson wrote:
>>
>>>
>>> I got that it you still haven't done anything to
>>> determine what the distinction is.
>>>
>>> Do the same thing, except bracket the exposure by 1/2
>>> and fstop, so that you can see the differences.
>>>
>>> How far does 1/2 an fstop move that red channel graph,
>>> compared to the 1mm (6 pixel) change you have above?
>> Quite a bit ... at contrast setting 0. I don't have my
>> camera with
>> me right now, so I can;t comment wuantitatively.
>>
>
>one more thing: I told you the last four digits of my Canon 30D's
>serial number.
>
>If you want to have any standing in this little Usenet flamefest,
>you should at least tell me the last four digits of YOUR
>Canon 30D serial number. At least, the number for the one you try
>it on!
>
>Do you have access to a 30D to try it on? Have you done so?

What logical basis do you have for insisting that your
Canon 30D is different than every other DSLR?

I'll grant that a model that old probably does not have
the nicest histogram display compared to newer cameras,
but rest assured that the contrast settings have *exactly*
the same effect as they do on a Nikon D3, or any of the
more recent Canon models either.

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

> 
> Exactly.  No matter what the constrast adjustment, a
> change in exposure moves all three channels by the same
> amount, until one clips.  Clipping happens with the same
> channel and at the same exposure no matter what your
> contrast setting is.
> 

in the raw file YES, on the on-camera histogram,
the resolution is too awful at contrast setting to be able to tell.

>> my point is that at contrast setting -4, I can see that there
>> is no clipping, whereas at contrast setting 0, I cannot see that ...
>> and in fact there is no clipping. This negates your point
>> without doing the "decrease exposure" test.
> 
> Okay, if that is true, try a scene with different
> illumination.  Try looking at a high key scene, then try
> looking at a low key scene.  If low contrast helps with
> one, high contrast will help with the other!
> 
> The point is still the same, contrast settings do *not*
> affect the exposure. 

Nor the raw file ... but they DO change the on-camera
histogram of a Canon 30D ... and my point is that at an in-camera
contrast setting 0, the utility of the histogram is such
that you can't get within 1/3 or 1/2 stop of clipping
(in the raw file) and be sure you are OK, while at
a camera setting of -4 you can tell.


> Your ability to read a histogram
> accurately is not of concern, and is variable not only
> with the contrast setting but also with the type of
> illumination.

It may vary with color temperature


> 
>> But I will do the decrease exposure test to see if, at
>> contrast level 0 (and I will try -2 also), it will move the
>> red channel away from the absolute right edge of the histogram.
> 
> If it doesn't, you are over exposing. 

Uh, NO NO NO  ... NO NO NO ... at the CURRENT exposure it is
NO OVER EXPOSING and at contrast setting 0 the histogram says it IS OVEREXPOSING
i.e. the histogram is wrong.


> And the point is
> that at contrast setting of -4, -2 and 0 the proper
> exposure is always going to be the same.

of course the proper exposure will be the same ... it is
just that at -4 I can tell from the histogram, at
0 I can't.


> 
>> But, still, with what I have said YIOU POINT IS NEGATED.
> 
> Not even close.
> 
>> You keep saying I don't understand ... but I **DO**
>>
>> READ WHAT I JUST SAID!!!
> 
> I have.
> 
>> In a condition where there is NO CLIPPING a contrast setting
>> -4 histogram allows me to see that, while one of zero does not.
>> That's teh bottom line. Can;t you see this?
> 
> Switch between high key lighting and low key lighting
> and tell me that it low contrast is an improvement for
> both! :-)

That I didn't do ... it was low key, and the highest
intensity area was a large area of white card.


> 
> You still miss the point that the proper exposure with
> high or low contrast settings is exactly the same. 

I do not miss the point. Of course the proper exposure is the same ...
it is not EXPOSURE I am talking about ... IT IS THE ON CAMERA HISTOGRAM
AND ITS REFLECTION, CORRECT OR INCORRECT, of the exposure.


  >If
> you read the histogram carefully, it makes no difference
> what the contrast setting is.

INCORRECT!! READ WHAT I SAID!!!


> There should not be any change at all in where you get
> correct exposure, *if* you read the histogram properly.
> The contrast setting does *not* change the exposure at
> which the maximum brightness hits the right side of the
> graph!

INCORRECT!!!



> 
> What changing to low contrast will do is move more of
> the data points closer to the right end of the graph,
> and for a low key scene that may help to read the graph
> while for an high key scene it might make it more
> difficult (because you cannot see the spike when
> clipping just begins, making perfect look identical to
> half a stop over exposed).
> 
>> BUT ... my point is made already.
> 
>> LET ME REPEAT, TRY TO UNDERSTAND:
>>
>> In a condition where there is NO CLIPPING a contrast setting
>> -4 histogram allows me to see that, while one of zero does not.
> 
> Clipping begins at exactly the same place, and it either
> has a data point at that level, or it doesn't.  Your
> point seems to be that you cannot closely examine a
> histogram graph for appropriate detail.  

I can examine the histogram all day with a microscope,
and at contrast setting 0, THE DETAIL IS NOT GOOD ENOUGH TO TELL.

If the camera had a three foot wide histogram display,
with 32000 pixels, you would indeed likely be correct!

But **I** am talking real world on a real camera.

I suggest you try a REAL Canon 30D.

Doug McDonald

"Floyd L. Davidson" <floyd@apaflo.com> wrote in message
news:87eipfql83.fld@apaflo.com

[...]

> The point is still the same, contrast settings do *not*
> affect the exposure.

Since nobody has said it does why don't you slow down and pay attention to 
what is being said?

What is being said is that where manufacturers draw the histogram settings 
from the compressed JPEG instead of the Raw image, lowering the contrast 
setting will render the histogram more accurately (closer to the Raw).  The 
claim is that this more accurate histogram *subsequently* enables the 
photographer to make more accurate adjustments to the exposure.

Check out the images under the heading "Contrast adjustment" on this page: 
http://www.dpreview.com/reviews/CanonEOS30D/page13.asp.  The luminosity 
histogram expands left and right as you increase the contrast.  If you were 
to judge by the +4 histogram you would think the image was clipping both 
highlights and shadows but this is not the case.

If the histogram at -4 is in fact more accurate than the histogram at 0 (the 
Canon default) then the photographer in fact has greater room for exposure 
compensation to the right than the histogram at contrast setting 0 
indicates.  For those wishing to compensate to the right this is useful 
information.  What the photographer *subsequently* chooses to do to the 
exposure is another discussion entirely. 

Paul Furman <paul-@-edgehill.net> wrote in news:haibte$5o3$1@news.eternal-
september.org:

> OK, the noise is more the reason but posterizing can be a problem in 
> dark areas...

The only cameras I know of with even a hint of RAW posterization are the 
Pentax K10D, which would profit from 13 bits instead of 12 at ISO 100 (not 
for 200 or higher), the Sony A900 also with a need for 13 bits at base, and 
the D3X when in 12-bit mode.  These are only on the fringe of posterizing.

> raising shadows in post for the deepest shadows, and in 
> skies where the color pallet is very limited. Doesn't the noise level 
> follow this same principle? Or is there an unrelated reason for the 
> noise levels paralleling tone counts?

Any posterization you see in a RAW conversion is most likely caused by the 
math used in the converter, and nothing else.  Of course, JPEG compression 
does some posterization of its own, especially if you use too much NR and 
it starts blocking up.

"Charles" <charlesschuler@comcast.net> wrote in
news:hagg86$ugf$1@news.eternal-september.org: 

>> Digital clipping is almost never "saturation of the
>> sensor".  Unless you are shooting at the base ISO
>> clipping is saturation of the Analog-Digital-Converter
>> (ADC) by sensor output that is greater than the maximum
>> ADC input.
> 
> And what difference would that make?  There is no sharper knee than
> one imposed by basic mathematics.  2^8 = 256, is a simple example. 
> With 8 bits, the maximum value is 255, base 10, with NO exceptions
> possible.  You actually help to make the case that over-exposed
> digital shots guarantee lost information in the bright portions of the
> scene. 

Exposure to the right is usually given as advice for RAW shooting.  The 
RAW data usually clips well above the level where a JPEG would clip it, 
and the trailing color channels, usually red or blue, are less sensitive 
and blow out in the RAW data much higher than in a JPEG.  For red, there 
is typically 2 stops more of highlight headroom in the red channel with 
daylight WB.  For the blue channel, 3 stops with tungsten WB.

Red is actuall being shot at double the ISO in daylight, and blue at 8x 
the ISO in incandescent light!
 
> I continue to believe that exposing to the right is perpetuated by
> folks with limited experience and knowledge.  They are perhaps into
> the dark parts of scenes and don't understand dynamic range.  Many of
> us are more greedy and want details at both ends of the luminosity
> range. 

That depends on how and why ETTR is used.  I don't see a whole lot of 
people recommending the act of blowing out the highlights to obtain ETTR.  
It is something you can do when you can; when you know it won't cause 
clipping.  The advantage in SNR is tremendous.  The shot noise, relative 
to signal, decreases when you increase absolute exposure (measured in 
absolute sensor exposure, ISO setting is irrelevant to shot noise except 
for potential clipping).  The read noise decreases, relative to signal, 
too, especially when you are using Canon-style CMOS where the read noise 
comes mainly at a later stage in the signal chain, and are very close in 
intensity at all low ISOs (up to 400 or 800).  With such cameras, you get 
a huge decrease in read noise (relative to signal) by using a higher ISO, 
if it doesn't cause clipping, without even increasing the absolute 
exposure.

> Hey, blow those high-lites out!

You're being ridiculous.  You are completely dismissing the idea of ETTR, 
based on a reckless strawman.  There is no connection between the idea of 
using ETTR when it is feasible, and using it haphazardly.

> If that is the intended message of a
> given scene, go for it.  I don't care for over-exposed shots ... they
> are just not my thing.  I have seen some high-key shots that were
> attractive and effective and do appreciate the skill and art of the
> photographers who can pull that off.
> 
> Specular high-lites might deserve to be blown out.  Not the point of
> my response.  I'll just say it one more time and then go away ... if
> it is clipped (by a sharp knee response curve ... due to sensor
> saturation or A/D saturation or any saturation link in the chain) it
> is GONE! 

If it is.  It may not be, however, if you shoot RAW.

For JPEGs, it is pretty trivial to set the camera up to produce low-
contrast JPEGs, and then use darkening gamma correction to pull the tones 
back down to saturated colors.  Low-contrast usually allows more of the 
RAW headroom to be used in the JPEG, and makes the highlight clipping 
indicator more accurate in most cases.  The only time it not clipping 
when something is really clipped in the RAW, IME, is when the highlight 
is bright blue against a dark background, because a weighted RGB 
histogram gives very little weight to blue.

floyd@apaflo.com (Floyd L. Davidson) wrote in 
news:87d450ucp2.fld@apaflo.com:

> The histogram will help you adjust your exposure, and
> that is *exactly* what I have said.  What I've also said
> is that changing the in-camera contrast setting does not
> change the histogram in any way that will affect
> exposure.  It does *not* change how close the graph approaches
> the right side.  All it does is change the distribution
> of the graph outward from the left side.

The left side of the histogram is only an artifact of conversion, and the 
arbitrary curve used on the X axis.  The top stops are usually made to look  
like each stop takes the same percentage of the entire histogram, but the 
left side suddenly turns linear, creating a left edge.  If the spacing used 
on the right side were used on the left, the left side of the histogram 
would never reach black; it would go on to infinity.

Talking about the left edge of a histogram is usually gibberish.  It is SNR 
which determines the quality of RAW shadows; not histogram positions. 

Porte Rouge wrote:
>
> I set my exposure to slide the histogram to the right, without clipping
> ( when I have time), to capture the most tonal levels . So, now when I
> am editing the photos they are over exposed(not clipped). A sunrise is
> a good example. The deep colors are washed out. The obvious fix(to me
> anyway) in Lightroom or CS4 is to reduce the exposure. Now my question
> is, by reducing exposure in post, am I just ending up in the same place
> (histogram to the left) as if I had just ignored the histogram when I
> was shooting and set the exposure to properly expose the image using
> my light meter? I guess in short I am asking if Lightroom or CS4 loses
> tonal values when you reduce exposure in editing.

Yes, reducing the exposure in Lightroom just puts your histogram back to the 
left, so that's a waste of time. To avoid having the deep colours washed 
out, you need to make use of the full tonal range available in the image. If 
you have done a good job of exposing to the right, your highlights will be 
pretty much where they need to be. So then all you need to do is raise the 
black point (e.g. using the Levels dialog in Photoshop), so that the dark 
tones in the scene end up as dark tones in the image. If you are using the 
Levels dialog in Photoshop, while you drag the black (or white) point 
slider, press the Alt key to see which pixels are clipped (or blown).

(The following relates to my experience with a Canon 450D. YMMV.)

There are two parts to exposing to the right - levels in the image and 
saturation of photosites. Whether you are shooting JPEG or raw, the camera's 
histogram display shows you the levels in a JPEG produced from the raw data, 
so the shape of the histogram curve depends on your settings for sharpness, 
contrast, saturation, colour tone, etc.

If you are shooting JPEG, all you can do is avoid piling up the histogram on 
the right, which prevents gross areas of blown highlights in the image.

If you are shooting raw, you can overexpose (beyond the point at which the 
histogram curve touches the right boundary), by about two steps and still 
produce an image from the raw without blown highlights. IOW, the headroom 
between blown highlights in the JPEG and saturation of the photosites is 
about two steps (in my experience, with the JPEG settings I use).

So if you are bracketing for the best possible exposure, go at least two 
steps over what the histogram tells you is "correct". The maximum possible 
dynamic range occurs at the point where photosites in the highlights begin 
to saturate.

In everyday raw shooting, you can be quite relaxed about having a small 
spike on the right of the histogram - that's actually a good thing. 

John Sheehy <JPS@no.komm> wrote:
>floyd@apaflo.com (Floyd L. Davidson) wrote in
>news:87d450ucp2.fld@apaflo.com:
>
>> The histogram will help you adjust your exposure, and
>> that is *exactly* what I have said.  What I've also said
>> is that changing the in-camera contrast setting does not
>> change the histogram in any way that will affect
>> exposure.  It does *not* change how close the graph approaches
>> the right side.  All it does is change the distribution
>> of the graph outward from the left side.
>
>The left side of the histogram is only an artifact of conversion, and the
>arbitrary curve used on the X axis.  The top stops are usually made to look
>like each stop takes the same percentage of the entire histogram, but the
>left side suddenly turns linear, creating a left edge.  If the spacing used
>on the right side were used on the left, the left side of the histogram
>would never reach black; it would go on to infinity.
>
>Talking about the left edge of a histogram is usually gibberish.  It is SNR
>which determines the quality of RAW shadows; not histogram positions.

I agree with all of the above.

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

"Wilba" <usenet@CUTTHISimago.com.au> wrote:
>Porte Rouge wrote:
>>
>> I set my exposure to slide the histogram to the right, without clipping
>> ( when I have time), to capture the most tonal levels . So, now when I
>> am editing the photos they are over exposed(not clipped). A sunrise is
>> a good example. The deep colors are washed out. The obvious fix(to me
>> anyway) in Lightroom or CS4 is to reduce the exposure. Now my question
>> is, by reducing exposure in post, am I just ending up in the same place
>> (histogram to the left) as if I had just ignored the histogram when I
>> was shooting and set the exposure to properly expose the image using
>> my light meter? I guess in short I am asking if Lightroom or CS4 loses
>> tonal values when you reduce exposure in editing.
>
>Yes, reducing the exposure in Lightroom just puts your histogram back to the
>left, so that's a waste of time.

Yes for the histogram, but it is not a waste of time.

Increasing the exposure adds signal, but the noise stays
the same.  In other words, if you take a shot of an
object that is all grey, with nothing approaching
"white" at all in the entire scene, you could

  1) Expose to produce an histogram that matches
     the scene, showing all values to be in the
     middle of the graph.  This will produce an
     accurately exposed JPEG too.

or,

  2) Expose to produce an histogram with the data
     pushed so far to the right that it is almost,
     but not quite, clipping.  The JPEG produce
     will be "overexposed", and instead of grey
     the scene will be white.

But we want an image made from the camera raw data, not
the JPEG.  And note that with either of the above
methods the "noise" in the data will be the same.  The
Signal to Noise Ratio (SNR) for method #2 will be higher
because the signal is higher.

The final image is made using the RAW converter, or an
image editor like Photoshop after conversion, to reduce
the whites down to grey.  And the same process will
*equally* reduce the noise.  Thus the noise in the final
image will be *lower* with method 2 than with method 1.

Reducing the amount of noise in the final product is
probably *not* a waste of time.

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

Floyd L. Davidson wrote:
> Paul Furman <paul-@-edgehill.net> wrote:
>> Floyd L. Davidson wrote:
>>> Doug McDonald <mcdonald@NoSpAmscs.uiuc.edu> wrote:
>>>> Floyd L. Davidson wrote:
>>>>
>>>>> But regardless of that, the cited URL above from
>>>>> luminous-landscape is *not* full of good stuff.  They
>>>>> miss the point entirely, and provide nothing that is
>>>>> actually useful!  All that changing in-camera contrast
>>>>> does is compress/uncompress the histograms idea of
>>>>> middle gray.  It does not change where the highlights
>>>>> fall, and thus does not change what you would set for
>>>>> the exposure.  (Does anyone ever look at the shape of an
>>>>> in-camera histogram and make adjustments as a result?
>>>>> It's a meaningless excercise, which will not change the
>>>>> camera raw data.  The shape of a post processing
>>>>> histogram is very useful, but not an in-camera
>>>>> histogram.)
>>>>>
>>>> What you say is wrong for the Canon 30D.  The histogram does
>>>> not change the raw data stored by the camera. But the camera setting DOES
>>>> change the camera displayed histogram. IF you set the camera "comtrast"
>>>> setting high, the highlights in the histogram get pushed way up
>>>> and are indeed useless for setting exposure. Ii you set it low,
>>>> at -3 or -4, the histogram displayed by the camera agrees quite nicely
>>>> with how close you are getting to clipping.
>>> The brightest part will still show at *exactly* the
>>> same
>>> place.
>> Maybe for contrast (though I doubt it) but WB makes a big difference. I
>> just tested at 25K & 100K, the highlights are completely different. I'm
>> looking at split RGB histograms btw.
> 
> That is exactly the point I *am* making.  WB changes the
> histogram in a useful way.  The Luminous-Landscape
> article did not talk about WB at all.  They discussed
> changing the camera's setting for contrast, and that
> simply does *nothing* useful for the histogram/exposure
> issue.
> 
> And if you doubt that the contrast setting will not change
> the histogram as stated, *try* *it*.  I gave an step by
> step description of a very easy way to show exactly what
> does and does not happen.  Why argue from supposition when
> you could actually learn something about photography...

I am interested in learning. I tried fiddling with the camera contrast 
settings to compare histograms and the difference was very minor, at 
least for the conditions I tried just now. I was thinking of 
post-processing where increasing contrast blows highlights & blocks 
shadows. Maybe not the very final edge of 100% saturation but contrast 
adjustments can make a big difference in what appears to be blown or 
blocked.  What you are describing sounds more like a gamma adjustment 
than contrast where only the middle part shifts.

An interesting related issue I don't understand is how the exposure 
slider works in Lightroom or ACR. I don't know how to duplicate that 
effect in photoshop with curves, levels, etc. Those all do like you 
describe, moving the middle parts of the histogram but there isn't an 
easy way I can see to shift the whole exposure. Hmm, the middle slider 
on levels comes close but still doesn't match the effect.

-- 
Paul Furman
www.edgehill.net
www.baynatives.com

all google groups messages filtered due to spam

John Sheehy wrote:
> Paul Furman wrote:
> 
>> OK, the noise is more the reason but posterizing can be a problem in 
>> dark areas...
> 
> The only cameras I know of with even a hint of RAW posterization are the 
> Pentax K10D, which would profit from 13 bits instead of 12 at ISO 100 (not 
> for 200 or higher), the Sony A900 also with a need for 13 bits at base, and 
> the D3X when in 12-bit mode.  These are only on the fringe of posterizing.
> 
>> raising shadows in post for the deepest shadows, and in 
>> skies where the color pallet is very limited. Doesn't the noise level 
>> follow this same principle? Or is there an unrelated reason for the 
>> noise levels paralleling tone counts?
> 
> Any posterization you see in a RAW conversion is most likely caused by the 
> math used in the converter, and nothing else.  Of course, JPEG compression 
> does some posterization of its own, especially if you use too much NR and 
> it starts blocking up.

OK, this makes sense, the posterizing issue is not really visible in any 
sort of normal exposure. What about Floyd's comment below that the noise 
level remains the same but exposing to the right increases the signal so 
that overwhelms the noise? That seems to tie the two together in a 
comprehensible way. The LL link just makes a lot of sense, it can't be 
complete BS. http://www.luminous-landscape.com/tutorials/expose-right.shtml

-- 
Paul Furman
www.edgehill.net
www.baynatives.com

all google groups messages filtered due to spam

DRS wrote:
> "Floyd L. Davidson" <floyd@apaflo.com> wrote in message
> news:87eipfql83.fld@apaflo.com
> 
> [...]
> 
>> The point is still the same, contrast settings do *not*
>> affect the exposure.
> 
> Since nobody has said it does why don't you slow down and pay attention to 
> what is being said?
> 
> What is being said is that where manufacturers draw the histogram settings 
> from the compressed JPEG instead of the Raw image, lowering the contrast 
> setting will render the histogram more accurately (closer to the Raw).  The 
> claim is that this more accurate histogram *subsequently* enables the 
> photographer to make more accurate adjustments to the exposure.
> 
> Check out the images under the heading "Contrast adjustment" on this page: 
> http://www.dpreview.com/reviews/CanonEOS30D/page13.asp.  The luminosity 
> histogram expands left and right as you increase the contrast.  If you were 
> to judge by the +4 histogram you would think the image was clipping both 
> highlights and shadows but this is not the case.
> 
> If the histogram at -4 is in fact more accurate than the histogram at 0 (the 
> Canon default) then the photographer in fact has greater room for exposure 
> compensation to the right than the histogram at contrast setting 0 
> indicates.  For those wishing to compensate to the right this is useful 
> information.  What the photographer *subsequently* chooses to do to the 
> exposure is another discussion entirely. 

What about saturation? Reducing saturation seems to give more detail to 
the edges also.

-- 
Paul Furman
www.edgehill.net
www.baynatives.com

all google groups messages filtered due to spam

On Wed, 07 Oct 2009 17:19:12 -0500, John Sheehy <JPS@no.komm> wrote:

>Exposure to the right is usually given as advice for RAW shooting.  The 
>RAW data usually clips well above the level where a JPEG would clip it, 

Very true, for all those cameras that intentionally do a poor job at the
RAW to JPG conversion. This is why RAW became so popular. DSLRs are
inherently poor at this process. In fact it's the very reason that having
access to the RAW data became so popular. Far too many DSLR owners wanted
to repair in their resulting images what the DSLR's firmware programmers
failed to do correctly in the first place. Companies then realized that
they could turn this into an asset. Not only sell a camera that didn't work
quite right, bundled with a kit-lens that wouldn't provide images any
better than a Barbie-Cam, conning them into buying a $5,000-$10,000 lens to
make their $500 DSLR functional, but now also sell them expensive editing
software to fix what their cameras weren't doing properly to provide a
useful image right out of the box.

A popular business model for the last couple of decades. Not unlike how
microsoft popularized this practice. They released Win95 in alpha phase (I
was a pre-beta-tester and read the in-house memos back then). M$ was
worried that they'd get sued worldwide for false-advertising if it wasn't
released on the promised date. In fact they were already behind several
deadlines and lawyers were starting to circle, ready to get their piece of
the M$ castle. M$ decided to go ahead and ship the alpha-phase Win95
anyway. What buyer would ever know. They then also charged (on a per-call
basis) their customers who bought this unfinished software for the
tech-support needed to get it running somewhat. A very effective means to
increase the profitability of an incomplete or improperly functioning
product. (This is why you should never buy any windows platform until after
the second or third service-pack is released. Let all the others happily
and foolishly pay for the privilege to be microsoft's beta-tester grunts.
When the reverse should be true. M$ should pay everyone to try out the
first few issues of their latest versions. If they're lucky, and they pay
all their beta-testers enough for all the time and work involved, we might
even tell M$ what is wrong.)

Sell them a DSLR that should work well and produce a useful image, but
doesn't. Then provide a $5,000-$10,000 lens and $200 software that they'll
need to get it working right.  It's just the M$ marketing strategy applied
to cameras, nothing more. Your valuable time that you spend in editing all
your RAW images for this privilege is merely a courtesy feature and should
go unmentioned, lest people become even more angry over how they've been
cunningly turned into more CEOs' saps.

There are many cameras now on the market where you will find little need
for RAW. Take the RAW data and try to get it to look better than the JPG
from the camera and you'll be hard pressed to better it. They manage to do
the process right the first time with no need for time-consuming RAW
editing intervention, other than setting white-balance and exposure
properly while shooting, as any decent photographer will and should.

Yes, they could easily provide the JPG images in the 16-bit HD-Photo format
(nearly all good editors fully support it) with compression ratio saving
options (as all editors do), for those of you that understand the need for
the extra data when trying to recover from your snapshooters' mistakes and
accidents. But then how could they sell the required RAW editing software
to you too? Not going to happen if they can find a simple way to make you
pay more of your money and waste even more of your valuable time.

Enjoy your crippled cameras. You got exactly what you were willing to pay
for.

"Paul Furman" <paul-@-edgehill.net> wrote in message
news:hajt19$8gj$1@news.eternal-september.org
> DRS wrote:

[...]

>> If the histogram at -4 is in fact more accurate than the histogram
>> at 0 (the Canon default) then the photographer in fact has greater
>> room for exposure compensation to the right than the histogram at
>> contrast setting 0 indicates.  For those wishing to compensate to
>> the right this is useful information.  What the photographer
>> *subsequently* chooses to do to the exposure is another discussion
>> entirely.
>
> What about saturation? Reducing saturation seems to give more detail
> to the edges also.

That is possible but not something for which I have evidence.  My concern 
here was to short-circuit this increasingly hysterical subthread by 
demonstrating that Floyd has been tilting at windmills.  Everything Doug 
McDonald has said about the effect on the histogram of changing the contrast 
setting on the 30D is borne out by the images on the page to which I linked. 
Since all the major DSLR manufacturers, to the best of my knowledge, derive 
histograms from the JPEGs then what he has described would be universally 
applicable. 

"DRS" <drs@removethis.ihug.com.au> wrote:
>"Paul Furman" <paul-@-edgehill.net> wrote in message
>news:hajt19$8gj$1@news.eternal-september.org
>> DRS wrote:
>
>[...]
>
>>> If the histogram at -4 is in fact more accurate than the histogram
>>> at 0 (the Canon default) then the photographer in fact has greater
>>> room for exposure compensation to the right than the histogram at
>>> contrast setting 0 indicates.  For those wishing to compensate to
>>> the right this is useful information.  What the photographer
>>> *subsequently* chooses to do to the exposure is another discussion
>>> entirely.
>>
>> What about saturation? Reducing saturation seems to give more detail
>> to the edges also.
>
>That is possible but not something for which I have evidence.  My concern
>here was to short-circuit this increasingly hysterical subthread by
>demonstrating that Floyd has been tilting at windmills.  Everything Doug
>McDonald has said about the effect on the histogram of changing the contrast
>setting on the 30D is borne out by the images on the page to which I linked.
>Since all the major DSLR manufacturers, to the best of my knowledge, derive
>histograms from the JPEGs then what he has described would be universally
>applicable.

The web page you cited has absolutely *nothing* on it
that supports what you or McDonald have said.  It talks
only about the effect of changing contrast settings on
the resulting JPEG image, not on the exposure or how it
affects camera raw data.

The histogram images show that *no* change in exposure
is demonstrated, and that *logically* it is not possible
to improve the accuracy of the histogram.  (Indeed, the
histograms shown are apparently purposely styled, with a
white foreground against a *grey* background and with a
grey scale at the bottom so that the lower right corner
has a white border against the white foreground.  They
have made it impossible to see where the right edge of
the data is!)

What it does show is that the peaks in the graph get
moved around, and if you *mistakenly* believe that where
the peak is at is related to exposure, you will
mistakenly think that contrast has somehow helped.

The problem with saying that contrast adjustments make
it more obvious where the right edge of the graph is at
is that different setting help or hinder with different
types of scenes.  For one scene you might well be right
that it is easier to see with low contrast, but just the
same for the next scene you shoot it could be high
contrast that would help.  It is *not* inherently better
for all purposes when set to low contrast!

Showing that it helps to see the edge in one condition
without being aware that the condition is a special
case, leads to a logically invalid conclusion.

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

"Floyd L. Davidson" <floyd@apaflo.com> wrote in message
news:87zl82qsmh.fld@apaflo.com
> "DRS" <drs@removethis.ihug.com.au> wrote:

[...]

>> That is possible but not something for which I have evidence.  My
>> concern here was to short-circuit this increasingly hysterical
>> subthread by demonstrating that Floyd has been tilting at windmills.
>> Everything Doug McDonald has said about the effect on the histogram
>> of changing the contrast setting on the 30D is borne out by the
>> images on the page to which I linked. Since all the major DSLR
>> manufacturers, to the best of my knowledge, derive histograms from
>> the JPEGs then what he has described would be universally applicable.
>
> The web page you cited has absolutely *nothing* on it
> that supports what you or McDonald have said.  It talks
> only about the effect of changing contrast settings on
> the resulting JPEG image, not on the exposure or how it
> affects camera raw data.

That is because they are two different things which nobody has conflated but 
you.  The images on that site show exactly what Doug McDonald claimed and 
nothing more.  Of course they show nothing on the effect on exposure or on 
Raw data but that was never the claim except in your mind.  You have created 
a straw man.

> The histogram images show that *no* change in exposure
> is demonstrated, and that *logically* it is not possible
> to improve the accuracy of the histogram.

It is possible to improve the accuracy of the histogram relative to the Raw 
data and the fact that you cannot see it when it is right before your eyes 
is your problem, not ours.  Those images show 5 different histograms where 
the only variable is the contrast setting.  Since the exposure has not 
changed then only one of the histograms can be the most accurate relative to 
the Raw image.  It happens to be the -4 setting.

[...]

> What it does show is that the peaks in the graph get
> moved around, and if you *mistakenly* believe that where
> the peak is at is related to exposure, you will
> mistakenly think that contrast has somehow helped.

Straw man.  All five histograms have different right-edges, indicating 
different possibilities for exposure compensation before clipping occurs. 
One of the 5 most accurately indicates the true feasible extent of ETTR, and 
that one is the -4 histogram.  That is all that has been claimed.

> The problem with saying that contrast adjustments make
> it more obvious where the right edge of the graph is at
> is that different setting help or hinder with different
> types of scenes.  For one scene you might well be right
> that it is easier to see with low contrast, but just the
> same for the next scene you shoot it could be high
> contrast that would help.  It is *not* inherently better
> for all purposes when set to low contrast!

The question of when ETTR is suitable is a different question again., and is 
not something I addressed.

> Showing that it helps to see the edge in one condition
> without being aware that the condition is a special
> case, leads to a logically invalid conclusion.

You are really not in any position to lecture on logic. 

"DRS" <drs@removethis.ihug.com.au> wrote:
>"Floyd L. Davidson" <floyd@apaflo.com> wrote in message
>news:87zl82qsmh.fld@apaflo.com
>> "DRS" <drs@removethis.ihug.com.au> wrote:
>
>[...]
>
>>> That is possible but not something for which I have evidence.  My
>>> concern here was to short-circuit this increasingly hysterical
>>> subthread by demonstrating that Floyd has been tilting at windmills.
>>> Everything Doug McDonald has said about the effect on the histogram
>>> of changing the contrast setting on the 30D is borne out by the
>>> images on the page to which I linked. Since all the major DSLR
>>> manufacturers, to the best of my knowledge, derive histograms from
>>> the JPEGs then what he has described would be universally applicable.
>>
>> The web page you cited has absolutely *nothing* on it
>> that supports what you or McDonald have said.  It talks
>> only about the effect of changing contrast settings on
>> the resulting JPEG image, not on the exposure or how it
>> affects camera raw data.
>
>That is because they are two different things which nobody has conflated but
>you.  The images on that site show exactly what Doug McDonald claimed and
>nothing more.  Of course they show nothing on the effect on exposure or on
>Raw data but that was never the claim except in your mind.  You have created
>a straw man.

It may show what Doug is talking about, but it shows
that it has nothing to do with correct exposure, which
*is* the point of this discussion.

You continue to say that effect on exposure in not
significant, but the *fact* is that is the *only* thing
that would be significant.  You *cannot* get more
accurate exposure without making the histogram more
accurate.  Contrast settings change the shape of the
graph between the right most edge and the the left edge
*but* *do* *not* *change* *the* *location* *of* *the* *right* *edge*.

Hence if the right edge is set correctly with high
contrast or low contrast, either way it is exactly the
same exposure and neither is more accurate than the
other.

You continue to say that low contrast makes it easier to
see where the edge is, but that is only true for special
cases, and for an equal number of special cases high
contrast would make it easier!

>> The histogram images show that *no* change in exposure
>> is demonstrated, and that *logically* it is not possible
>> to improve the accuracy of the histogram.
>
>It is possible to improve the accuracy of the histogram relative to the Raw
>data and the fact that you cannot see it when it is right before your eyes
>is your problem, not ours.  Those images show 5 different histograms where
>the only variable is the contrast setting.  Since the exposure has not
>changed then only one of the histograms can be the most accurate relative to
>the Raw image.  It happens to be the -4 setting.

All five show *exactly* the same exposure.  I assume you
are looking at the large peaks of the graph as they move
more towards the right edge.  That of course is *not* a
measure of exposure.

If the graphs were designed to show the effect they
would also have to show histograms for some lower
exposure and at some higher exposure, to demonstrate
what one has to adjust for.

>
>[...]
>
>> What it does show is that the peaks in the graph get
>> moved around, and if you *mistakenly* believe that where
>> the peak is at is related to exposure, you will
>> mistakenly think that contrast has somehow helped.
>
>Straw man.  All five histograms have different right-edges, indicating
>different possibilities for exposure compensation before clipping occurs.
>One of the 5 most accurately indicates the true feasible extent of ETTR, and
>that one is the -4 histogram.  That is all that has been claimed.

They all have exactly the same right edge, to the degree
that it can be determined (which is exceedingly
difficult because the images were designed purposely to
de-emphasize that and to emphasize the changes that
contrast actually does cause.  That of course is
perfectly reasonable because that is the topic they are
discussing, and is the reason they do not mention
exposure at all.

>> The problem with saying that contrast adjustments make
>> it more obvious where the right edge of the graph is at
>> is that different setting help or hinder with different
>> types of scenes.  For one scene you might well be right
>> that it is easier to see with low contrast, but just the
>> same for the next scene you shoot it could be high
>> contrast that would help.  It is *not* inherently better
>> for all purposes when set to low contrast!
>
>The question of when ETTR is suitable is a different question again., and is
>not something I addressed.

The above has nothing at all to do with suitability of
ETTR, it is not something I've addressed either.  Why
are you?

>> Showing that it helps to see the edge in one condition
>> without being aware that the condition is a special
>> case, leads to a logically invalid conclusion.
>
>You are really not in any position to lecture on logic.

Other than I use it, and you don't?  Seems like a good
position...

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

On Mon, 05 Oct 2009 15:23:57 -0800, Floyd L. Davidson wrote:

[re film's "expose for shadows", digital's "expose for the highlights"] 
> Actually, since film is a negative, the two are in fact
> actually the same.  Expose for the brightest range of the
> *recording* *mechanism*.
> 
> That just happens to be the dark areas of a scene with
> film (where the negative is clear) and the bright areas
> of a scene with an electronic sensor (the highest
> voltage output).

No - both refer to areas of the scene.  The full rule of thumb for film is
"Expose for the shadows.  Develop for the highlights".  Exposing for the
shadows establishes the area of minimum negative density, and development
has a much greater effect on the highlights than the shadows.

For digital, exposing for the highlights amounts to playing chicken with
the brightest significant information in the image, by choosing an exposure
and ISO that puts the brightest significant subject material as close as
possible to the max sensor value, without actually losing information.

Your other points are technically true, but belie the fact that film's
Achilles heel is loss of subject shadow detail, while digital's is loss of
subject highlight detail.
<snip>
-- 
Mike Russell - http://www.curvemeister.com

"Floyd L. Davidson" <floyd@apaflo.com> wrote in message
news:87vdiqqqso.fld@apaflo.com
> "DRS" <drs@removethis.ihug.com.au> wrote:

[...]

>> That is because they are two different things which nobody has
>> conflated but you.  The images on that site show exactly what Doug
>> McDonald claimed and nothing more.  Of course they show nothing on
>> the effect on exposure or on Raw data but that was never the claim
>> except in your mind.  You have created a straw man.
>
> It may show what Doug is talking about, but it shows
> that it has nothing to do with correct exposure, which
> *is* the point of this discussion.

More accurate histograms are part of the information a photographer needs in 
order to make good decisions about what *subsequently* to do about the 
exposure settings.

> You continue to say that effect on exposure in not
> significant, but the *fact* is that is the *only* thing
> that would be significant.

Nobody ever said any such thing.  Stop making shit up.

> You *cannot* get more
> accurate exposure without making the histogram more
> accurate.

Of course. That is what has been said all along.

>  Contrast settings change the shape of the
> graph between the right most edge and the the left edge
> *but* *do* *not* *change* *the* *location* *of* *the* *right* *edge*.

Yes, they do.  Everybody sees it except you.  Increase the contrast setting 
and the histogram expands left and right.  Decrease contrast and the edges 
shift inwards especially on the right edge.  The change in the location of 
the right edge between -4 and +4 stands out like dog's balls.

[...]

> You continue to say that low contrast makes it easier to
> see where the edge is,

No, what has been said is that changing the contrast setting changes the 
location of the right edge, which in turn renders the histogram more or less 
accurate.  Low contrast shifts the right edge to the left and the claim is 
that this more accurately resembles the Raw data.

[...]

>> It is possible to improve the accuracy of the histogram relative to
>> the Raw data and the fact that you cannot see it when it is right
>> before your eyes is your problem, not ours.  Those images show 5
>> different histograms where the only variable is the contrast
>> setting.  Since the exposure has not changed then only one of the
>> histograms can be the most accurate relative to the Raw image.  It
>> happens to be the -4 setting.
>
> All five show *exactly* the same exposure.

That is not in dispute.  If you payed attention you'd have noticed that in 
that very paragraph I said, "Since the exposure has not changed..."  The 
fact that the exposure is the same is necessary to the point being made, 
which is that changing one and only one variable, the contrast setting, 
changes the accuracy of the histogram upon which decisions about exposure 
are *subsequently* made.  I keep putting the word "subsequently" in bold 
because you just don't get it.  Decisions about exposure come after the 
point under discussion.

[...]

> They all have exactly the same right edge, to the degree
> that it can be determined (which is exceedingly

No, they don't.  Blind Freddy can see the right-edges shift by at least 1 
stop from -4 to +4, and probably more.  And before you jump on your exposure 
hobby-horse don't.  That has nothing to do with the actual exposure 
settings.  It is simply an indication of the real amount of exposure 
compensation that is possible before clipping occurs.

[...]

>> You are really not in any position to lecture on logic.
>
> Other than I use it, and you don't?  Seems like a good
> position...

The proof is in the pudding is in the eating. 

Mike Russell <groupsRE@MOVEcurvemeister.com> wrote:
>On Mon, 05 Oct 2009 15:23:57 -0800, Floyd L. Davidson wrote:
>
>[re film's "expose for shadows", digital's "expose for the highlights"]
>> Actually, since film is a negative, the two are in fact
>> actually the same.  Expose for the brightest range of the
>> *recording* *mechanism*.
>>
>> That just happens to be the dark areas of a scene with
>> film (where the negative is clear) and the bright areas
>> of a scene with an electronic sensor (the highest
>> voltage output).
>
>No - both refer to areas of the scene.  The full rule of thumb for film is
>"Expose for the shadows.  Develop for the highlights".  Exposing for the
>shadows establishes the area of minimum negative density, and development
>has a much greater effect on the highlights than the shadows.
>
>For digital, exposing for the highlights amounts to playing chicken with
>the brightest significant information in the image, by choosing an exposure
>and ISO that puts the brightest significant subject material as close as
>possible to the max sensor value, without actually losing information.
>
>Your other points are technically true, but belie the fact that film's
>Achilles heel is loss of subject shadow detail, while digital's is loss of
>subject highlight detail.
><snip>

Interesting way to say, "No, you are right."

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

"DRS" <drs@removethis.ihug.com.au> wrote:
>"Floyd L. Davidson" <floyd@apaflo.com> wrote in message
>news:87vdiqqqso.fld@apaflo.com
>>  Contrast settings change the shape of the
>> graph between the right most edge and the the left edge
>> *but* *do* *not* *change* *the* *location* *of* *the* *right* *edge*.
>
>Yes, they do.  Everybody sees it except you.  Increase the contrast setting
>and the histogram expands left and right.  Decrease contrast and the edges
>shift inwards especially on the right edge.  The change in the location of
>the right edge between -4 and +4 stands out like dog's balls.

....

>>> It is possible to improve the accuracy of the histogram relative to
>>> the Raw data and the fact that you cannot see it when it is right
>>> before your eyes is your problem, not ours.  Those images show 5
>>> different histograms where the only variable is the contrast
>>> setting.  Since the exposure has not changed then only one of the
>>> histograms can be the most accurate relative to the Raw image.  It
>>> happens to be the -4 setting.
>>
>> All five show *exactly* the same exposure.
>
>That is not in dispute.  If you payed attention you'd have noticed that in
>that very paragraph I said, "Since the exposure has not changed..."  The
>fact that the exposure is the same is necessary to the point being made,
>which is that changing one and only one variable, the contrast setting,
>changes the accuracy of the histogram upon which decisions about exposure
>are *subsequently* made.

You can't have it both ways.  First you say that the
contrast setting moves the histogram's indication of
exposure, and now you say it does not.

All five of those histograms show *exactly* the same
exposure, even though they have 5 different contrast
settings.

If that is the desired exposure, not one of those
histograms would suggest that the camera's exposure
should be changed to be more accurate.

>> They all have exactly the same right edge, to the degree
>> that it can be determined (which is exceedingly
>
>No, they don't.  Blind Freddy can see the right-edges shift by at least 1
>stop from -4 to +4, and probably more.

You apparently are looking at that huge peak value to
the left of the right edge, as it is the only thing that
moves by "at least 1 stop".  But that peak has *nothing*
to do with setting correct exposure.  See the little
itty bitty value down in the lower right hand corner?

That is the value of significance.  That is the "right
edge".

>>> You are really not in any position to lecture on logic.
>>
>> Other than I use it, and you don't?  Seems like a good
>> position...
>
>The proof is in the pudding is in the eating.

Cute. I'll settle for being logical.

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

"Floyd L. Davidson" <floyd@apaflo.com> wrote in message
news:87eipeqnt0.fld@apaflo.com
> "DRS" <drs@removethis.ihug.com.au> wrote:

[...]

>> That is not in dispute.  If you payed attention you'd have noticed
>> that in that very paragraph I said, "Since the exposure has not
>> changed..."  The fact that the exposure is the same is necessary to
>> the point being made, which is that changing one and only one
>> variable, the contrast setting, changes the accuracy of the
>> histogram upon which decisions about exposure are *subsequently*
>> made.
>
> You can't have it both ways.  First you say that the
> contrast setting moves the histogram's indication of
> exposure, and now you say it does not.

I have always said it changes the indication of exposure.  It is you who 
made the false claim that I and others were saying it had anything to do 
with changing the actual exposure, which we have repeatedly denied.

> All five of those histograms show *exactly* the same
> exposure, even though they have 5 different contrast
> settings.

And because of the different contrast settings the 5 histograms show the 
exposure differently.  The exposure hasn't changed but the accuracy of its 
representation has.  Which is all that has been claimed.

> If that is the desired exposure, not one of those
> histograms would suggest that the camera's exposure
> should be changed to be more accurate.

None of the 5 histograms indicate overexposure.  What they do indicate, to 
different degrees of accuracy, is the room for exposure compensation.  Only 
1 can be the most accurate and it is the -4 histogram.

[...]

>> No, they don't.  Blind Freddy can see the right-edges shift by at
>> least 1 stop from -4 to +4, and probably more.
>
> You apparently are looking at that huge peak value to
> the left of the right edge, as it is the only thing that
> moves by "at least 1 stop".  But that peak has *nothing*
> to do with setting correct exposure.  See the little
> itty bitty value down in the lower right hand corner?
>
> That is the value of significance.  That is the "right
> edge".

In this instance that indicates specular highlights, which as has been noted 
by several people, may be blown without spoiling the image.  That is a 
choice by the photographer.

[...]

>> The proof is in the pudding is in the eating.
>
> Cute. I'll settle for being logical.

Good.  I hope to see it soon. 

"DRS" <drs@removethis.ihug.com.au> wrote:
>"Floyd L. Davidson" <floyd@apaflo.com> wrote in message
>news:87eipeqnt0.fld@apaflo.com
>> "DRS" <drs@removethis.ihug.com.au> wrote:
>
>[...]
>
>>> That is not in dispute.  If you payed attention you'd have noticed
>>> that in that very paragraph I said, "Since the exposure has not
>>> changed..."  The fact that the exposure is the same is necessary to
>>> the point being made, which is that changing one and only one
>>> variable, the contrast setting, changes the accuracy of the
>>> histogram upon which decisions about exposure are *subsequently*
>>> made.
>>
>> You can't have it both ways.  First you say that the
>> contrast setting moves the histogram's indication of
>> exposure, and now you say it does not.
>
>I have always said it changes the indication of exposure.  It is you who
>made the false claim that I and others were saying it had anything to do
>with changing the actual exposure, which we have repeatedly denied.
>
>> All five of those histograms show *exactly* the same
>> exposure, even though they have 5 different contrast
>> settings.

*All* *five* *show* *the* *exact* *same* *exposure*.

Not one of them shows any 1 f/stop difference as you
claim.

The only thing that moves 1 f/stop are the tall peaks in
the graph that have *nothing* to do with exposure.  It
is well to the left of the right edge, and it is that
right edge that indicates exposure.

>And because of the different contrast settings the 5 histograms show the
>exposure differently.  The exposure hasn't changed but the accuracy of its
>representation has.  Which is all that has been claimed.

They *don't* show the *exposure* differently.

>> If that is the desired exposure, not one of those
>> histograms would suggest that the camera's exposure
>> should be changed to be more accurate.
>
>None of the 5 histograms indicate overexposure.  What they do indicate, to
>different degrees of accuracy, is the room for exposure compensation.  Only
>1 can be the most accurate and it is the -4 histogram.

All of them indicate there is no room for any
"compensation".  Increasing the camera exposure will
result in clipping, and each of those histograms shows
that.

Oddly enough, the +4 histogram shows it the best!

>>> No, they don't.  Blind Freddy can see the right-edges shift by at
>>> least 1 stop from -4 to +4, and probably more.
>>
>> You apparently are looking at that huge peak value to
>> the left of the right edge, as it is the only thing that
>> moves by "at least 1 stop".  But that peak has *nothing*
>> to do with setting correct exposure.  See the little
>> itty bitty value down in the lower right hand corner?
>>
>> That is the value of significance.  That is the "right
>> edge".
>
>In this instance that indicates specular highlights, which as has been noted
>by several people, may be blown without spoiling the image.  That is a
>choice by the photographer.

The tall peaks are *not* a "specular highlights", and
one look at the image should demonstrate that there are
no light sources or reflections in the image.  Those
peaks are probably the whiter parts of the background,
but might be from one or more of the crayons too.  It
isn't possible to determine from looking at the
histograms just where the actual values are that make up
either those peaks or the right edge of the histogram.
It does appear that the whitest part of the watch face,
around the 12 and 6, are probably where the right edge of
the histogram values are from.

Note that only in the +4 histogram are the values at the
right edge more than maybe 2 pixels high on that graph.
They are very hard to see because of the white portion
of the gray scale below the graph and the lack of
contrast with the gray background.

>>> The proof is in the pudding is in the eating.
>>
>> Cute. I'll settle for being logical.
>
>Good.  I hope to see it soon.

With a bit of logic you'd have seen it already.

You know, logically if what you said made sense the
article would have discussed it in some way, but it does
not even hint at it.  If changing the contrast displayed
a more accurate *exposure* (right edge location), why
didn't they point to it?

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

Paul Furman <paul-@-edgehill.net> wrote:
>Floyd L. Davidson wrote:
>> That is exactly the point I *am* making.  WB changes
>> the
>> histogram in a useful way.  The Luminous-Landscape
>> article did not talk about WB at all.  They discussed
>> changing the camera's setting for contrast, and that
>> simply does *nothing* useful for the histogram/exposure
>> issue.
>> And if you doubt that the contrast setting will not
>> change
>> the histogram as stated, *try* *it*.  I gave an step by
>> step description of a very easy way to show exactly what
>> does and does not happen.  Why argue from supposition when
>> you could actually learn something about photography...
>
>I am interested in learning. I tried fiddling with the camera contrast
>settings to compare histograms and the difference was very minor, at
>least for the conditions I tried just now. I was thinking of
>post-processing where increasing contrast blows highlights & blocks
>shadows. Maybe not the very final edge of 100% saturation but contrast
>adjustments can make a big difference in what appears to be blown or
>blocked.  What you are describing sounds more like a gamma adjustment
>than contrast where only the middle part shifts.

  "Gamma is equivalent to contrast. This can be observed
  in traditional film curves, which are displayed on
  logarithmic scales (typically, density (log10(absorbed
  light) vs. log10(exposure)). Gamma is the average
  slope of this curve (excluding the "toe" and
  "shoulder" regions near the ends of the curve), i.e.,
  the contrast."
     http://www.imatest.com/docs/glossary.html
     (The above is a web page owned by Norman Koren.)

  "Gamma -- A way of representing the contrast of an
  image, shown as the slope of a curve showing tones
  from white to black."
     http://www.hp.com/united-states/consumer/digital_photography/articles/scanner_glossary.html

That might help make things clearer as to why changing
contrast does not make the histogram any more or less
accurate for exposure.

When the histogram indicates precisely the correct
exposure, changing the gamma (contrast) moves the curve
between black and maximum white values, but it doesn't
change the value of either.  Note too that it might
spread the histogram out from the center (if the gamma
curve is moved by picking a point at its center), or it
might move towards ether the right or the left (if the
gamma curve is moved from point closer to the ends
instead of at the center).

In any case, it changes the contrast but if there are
image values at the maximum white value they will not be
moved.

>An interesting related issue I don't understand is how the exposure
>slider works in Lightroom or ACR. I don't know how to duplicate that
>effect in photoshop with curves, levels, etc. Those all do like you
>describe, moving the middle parts of the histogram but there isn't an
>easy way I can see to shift the whole exposure. Hmm, the middle slider
>on levels comes close but still doesn't match the effect.

I don't use those programs so I can only provide general
instructions about how that is typically done.  I'll
leave it to someone who can be more specific.

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

Paul Furman <paul-@-edgehill.net> wrote:
>John Sheehy wrote:
>> Paul Furman wrote:
>>
>>> OK, the noise is more the reason but posterizing can
>>> be a problem in dark areas...
>> The only cameras I know of with even a hint of RAW
>> posterization are the Pentax K10D, which would profit
>> from 13 bits instead of 12 at ISO 100 (not for 200 or
>> higher), the Sony A900 also with a need for 13 bits at
>> base, and the D3X when in 12-bit mode.  These are only
>> on the fringe of posterizing.
>>
>>> raising shadows in post for the deepest shadows, and
>>> in skies where the color pallet is very
>>> limited. Doesn't the noise level follow this same
>>> principle? Or is there an unrelated reason for the
>>> noise levels paralleling tone counts?
>> Any posterization you see in a RAW conversion is most
>> likely caused by the math used in the converter, and
>> nothing else.  Of course, JPEG compression does some
>> posterization of its own, especially if you use too
>> much NR and it starts blocking up.
>
>OK, this makes sense, the posterizing issue is not really visible in any
>sort of normal exposure. What about Floyd's comment below that the noise
>level remains the same but exposing to the right increases the signal so
>that overwhelms the noise? That seems to tie the two together in a
>comprehensible way. The LL link just makes a lot of sense, it can't be
>complete BS. http://www.luminous-landscape.com/tutorials/expose-right.shtml

That is an *excellent* article.  It also has a link to
another article, titled "Understanding Histograms",
which several contributors to this thread could benefit
from (particularly the histogram of the moon shot and
the high key tree image that are the last two shown at
the bottom of the article):

  http://www.luminous-landscape.com/tutorials/understanding-series/understanding-histograms.shtml

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

"Floyd L. Davidson" <floyd@apaflo.com> wrote in message
news:87ab02ql1h.fld@apaflo.com
> "DRS" <drs@removethis.ihug.com.au> wrote:

[...]

>> I have always said it changes the indication of exposure.  It is you
>> who made the false claim that I and others were saying it had
>> anything to do with changing the actual exposure, which we have
>> repeatedly denied.
>
> *All* *five* *show* *the* *exact* *same* *exposure*.

Yes, how many times do I have to tell you that before you get it?

> Not one of them shows any 1 f/stop difference as you
> claim.

Yes, they do, in terms of *accuracy*.

> The only thing that moves 1 f/stop are the tall peaks in
> the graph that have *nothing* to do with exposure.  It
> is well to the left of the right edge, and it is that
> right edge that indicates exposure.

The right edge moves.

>> And because of the different contrast settings the 5 histograms show
>> the exposure differently.  The exposure hasn't changed but the
>> accuracy of its representation has.  Which is all that has been
>> claimed.
>
> They *don't* show the *exposure* differently.

Yes, they do.  Everybody can see it except you.

>> None of the 5 histograms indicate overexposure.  What they do
>> indicate, to different degrees of accuracy, is the room for exposure
>> compensation.  Only 1 can be the most accurate and it is the -4
>> histogram.
>
> All of them indicate there is no room for any
> "compensation".  Increasing the camera exposure will
> result in clipping, and each of those histograms shows
> that.

No, they don't.  Try looking at what is there.

[...]

>> In this instance that indicates specular highlights, which as has
>> been noted by several people, may be blown without spoiling the
>> image.  That is a choice by the photographer.
>
> The tall peaks are *not* a "specular highlights", and

I didn't say they were.  Do you ever pay attention?  You can't even follow 
when I'm addressing your argument!

[...]

> You know, logically if what you said made sense the
> article would have discussed it in some way, but it does
> not even hint at it.  If changing the contrast displayed
> a more accurate *exposure* (right edge location), why
> didn't they point to it?

"What does all this mean?  In order to display the full dynamic range of 
your camera in the histogram displayed on the back, you must set the 
contrast to minimum.  You now can see the same dynamic range in the 
histogram on the camera as you will see it in your RAW processor on your 
computer." 

On Oct 8, 6:22=A0am, fl...@apaflo.com (Floyd L. Davidson) wrote:
> Paul Furman <pa...@-edgehill.net> wrote:
> >John Sheehy wrote:
> >> Paul Furman wrote:
>
> >>> OK, the noise is more the reason but posterizing can
> >>> be a problem in dark areas...
> >> The only cameras I know of with even a hint of RAW
> >> posterization are the Pentax K10D, which would profit
> >> from 13 bits instead of 12 at ISO 100 (not for 200 or
> >> higher), the Sony A900 also with a need for 13 bits at
> >> base, and the D3X when in 12-bit mode. =A0These are only
> >> on the fringe of posterizing.
>
> >>> raising shadows in post for the deepest shadows, and
> >>> in skies where the color pallet is very
> >>> limited. Doesn't the noise level follow this same
> >>> principle? Or is there an unrelated reason for the
> >>> noise levels paralleling tone counts?
> >> Any posterization you see in a RAW conversion is most
> >> likely caused by the math used in the converter, and
> >> nothing else. =A0Of course, JPEG compression does some
> >> posterization of its own, especially if you use too
> >> much NR and it starts blocking up.
>
> >OK, this makes sense, the posterizing issue is not really visible in any
> >sort of normal exposure. What about Floyd's comment below that the noise
> >level remains the same but exposing to the right increases the signal so
> >that overwhelms the noise? That seems to tie the two together in a
> >comprehensible way. The LL link just makes a lot of sense, it can't be
> >complete BS.http://www.luminous-landscape.com/tutorials/expose-right.sht=
ml
>
> That is an *excellent* article. =A0It also has a link to
> another article, titled "Understanding Histograms",
> which several contributors to this thread could benefit
> from (particularly the histogram of the moon shot and
> the high key tree image that are the last two shown at
> the bottom of the article):
>
> =A0http://www.luminous-landscape.com/tutorials/understanding-series/unde.=
...
>
> --
> Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
> Ukpeagvik (Barrow, Alaska) =A0 =A0 =A0 =A0 =A0 =A0 =A0fl...@apaflo.com

Hey, that's the same article you said this about:

"But regardless of that, the cited URL above from
luminous-landscape is *not* full of good stuff.  They
miss the point entirely, and provide nothing that is
actually useful!"

On Oct 7, 8:21=A0pm, "Wilba" <use...@CUTTHISimago.com.au> wrote:
> Porte Rouge wrote:
>
> > I set my exposure to slide the histogram to the right, without clipping
> > ( when I have time), to capture the most tonal levels . So, now when I
> > am editing the photos they are over exposed(not clipped). A sunrise is
> > a good example. The deep colors are washed out. The obvious fix(to me
> > anyway) in Lightroom or CS4 is to reduce the exposure. Now my question
> > is, by reducing exposure in post, am I just ending up in the same place
> > (histogram to the left) as if I had just ignored the histogram when I
> > was shooting and set the exposure to properly expose the image using
> > my light meter? I guess in short I am asking if Lightroom or CS4 loses
> > tonal values when you reduce exposure in editing.
>
> Yes, reducing the exposure in Lightroom just puts your histogram back to =
the
> left, so that's a waste of time. To avoid having the deep colours washed
> out, you need to make use of the full tonal range available in the image.=
 If
> you have done a good job of exposing to the right, your highlights will b=
e
> pretty much where they need to be. So then all you need to do is raise th=
e
> black point (e.g. using the Levels dialog in Photoshop), so that the dark
> tones in the scene end up as dark tones in the image. If you are using th=
e
> Levels dialog in Photoshop, while you drag the black (or white) point
> slider, press the Alt key to see which pixels are clipped (or blown).
>
> (The following relates to my experience with a Canon 450D. YMMV.)

Aha!

>
> There are two parts to exposing to the right - levels in the image and
> saturation of photosites. Whether you are shooting JPEG or raw, the camer=
a's
> histogram display shows you the levels in a JPEG produced from the raw da=
ta,
> so the shape of the histogram curve depends on your settings for sharpnes=
s,
> contrast, saturation, colour tone, etc.
>
> If you are shooting JPEG, all you can do is avoid piling up the histogram=
 on
> the right, which prevents gross areas of blown highlights in the image.
>
> If you are shooting raw, you can overexpose (beyond the point at which th=
e
> histogram curve touches the right boundary), by about two steps and still
> produce an image from the raw without blown highlights. IOW, the headroom
> between blown highlights in the JPEG and saturation of the photosites is
> about two steps (in my experience, with the JPEG settings I use).
>
> So if you are bracketing for the best possible exposure, go at least two
> steps over what the histogram tells you is "correct". The maximum possibl=
e
> dynamic range occurs at the point where photosites in the highlights begi=
n
> to saturate.
>

What do you mean by steps? Do you mean stops, or steps on the aperture
or shutter dials?


> In everyday raw shooting, you can be quite relaxed about having a small
> spike on the right of the histogram - that's actually a good thing.

Floyd L. Davidson wrote:


I have performed tests on my Canon 30D camera to see
what happens if I expose less. I exposed 1/3 and 2/3
stops less than before.

At 2/3 stop less than before yes, even at contrast setting zero,
I do see a teensy bit of space between the top of the red histogram
and the top of the display. This means that if I'm willing to
lose 2/3 stop of unclipped data at the bright end, Floyd is "effectively"
right.

But if I want that extra 2/3 stop, I'm still correct.

I should add that my method works --- I use -4 in the camera,
use the histogram, and find my raw images are very nicely exposed,
no clipping (except as desired for specular highlights) and the
data right up to the clipping level.

Doug McDonald

Floyd L. Davidson wrote:

> Hence if the right edge is set correctly with high
> contrast or low contrast, either way it is exactly the
> same exposure and neither is more accurate than the
> other.
> 
> You continue to say that low contrast makes it easier to
> see where the edge is, but that is only true for special
> cases, and for an equal number of special cases high
> contrast would make it easier!
> 

In NO CASE would high contrast make it easier ...
at least on a Canon 30D.

Mr. Davidson: Let me ask again: What is the serial
number of the Canon 30D you have checked this on.

If you have not done so, SHUT UP.

We admit that you are right if somebody using
a Canon 30D is willing to allow 2/3 stop more "slop"
than is really necessary.


Doug McDonald

Floyd L. Davidson wrote:
> Paul Furman <paul-@-edgehill.net> wrote:
>> Floyd L. Davidson wrote:
>>> That is exactly the point I *am* making.  WB changes
>>> the histogram in a useful way.  The Luminous-Landscape
>>> article did not talk about WB at all.  They discussed
>>> changing the camera's setting for contrast, and that
>>> simply does *nothing* useful for the histogram/exposure
>>> issue. And if you doubt that the contrast setting will not
>>> change the histogram as stated, *try* *it*.  I gave an step by
>>> step description of a very easy way to show exactly what
>>> does and does not happen.  Why argue from supposition when
>>> you could actually learn something about photography...
>> 
>> I am interested in learning. I tried fiddling with the camera contrast
>> settings to compare histograms and the difference was very minor, at
>> least for the conditions I tried just now.

A second try showed a significant difference.


>> I was thinking of
>> post-processing where increasing contrast blows highlights & blocks
>> shadows. Maybe not the very final edge of 100% saturation but contrast
>> adjustments can make a big difference in what appears to be blown or
>> blocked.  What you are describing sounds more like a gamma adjustment
>> than contrast where only the middle part shifts.

Scratch that comment, they both have an effect.


>   "Gamma is equivalent to contrast.

I dunno, maybe your linked definers are thinking of a different context. 
Common sense and experience tell me gamma is adjusting the middle-value, 
more like brightness, without changing the the ends. Contrast 
adjustments tend to hold the mid-point and use an s curve to raise 
highlights & lower shadows or the inverse. A gamma adjustment curve is a 
fairly simple bowed shape, not an s shape. Sure a gamma adjustment has 
an effect on contrast but that's a side effect, not the goal. Gamma 
adjustments boost contrast in either the highlights or shadows, not both.


>   This can be observed
>   in traditional film curves, which are displayed on
>   logarithmic scales (typically, density (log10(absorbed
>   light) vs. log10(exposure)). Gamma is the average
>   slope of this curve (excluding the "toe" and
>   "shoulder" regions near the ends of the curve), i.e.,
>   the contrast."
>      http://www.imatest.com/docs/glossary.html
>      (The above is a web page owned by Norman Koren.)
> 
>   "Gamma -- A way of representing the contrast of an
>   image, shown as the slope of a curve showing tones
>   from white to black."
>      http://www.hp.com/united-states/consumer/digital_photography/articles/scanner_glossary.html
> 
> That might help make things clearer as to why changing
> contrast does not make the histogram any more or less
> accurate for exposure.
> 
> When the histogram indicates precisely the correct
> exposure, changing the gamma (contrast) moves the curve
> between black and maximum white values, but it doesn't
> change the value of either.  Note too that it might
> spread the histogram out from the center (if the gamma
> curve is moved by picking a point at its center), or it
> might move towards ether the right or the left (if the
> gamma curve is moved from point closer to the ends
> instead of at the center).
> 
> In any case, it changes the contrast but if there are
> image values at the maximum white value they will not be
> moved.

The maximum white value may be already off the edge so you are talking 
about part of the middle of the curve, which is effected, showing more 
detail with low contrast.


>> An interesting related issue I don't understand is how the exposure
>> slider works in Lightroom or ACR. I don't know how to duplicate that
>> effect in photoshop with curves, levels, etc. Those all do like you
>> describe, moving the middle parts of the histogram but there isn't an
>> easy way I can see to shift the whole exposure. Hmm, the middle slider
>> on levels comes close but still doesn't match the effect.
> 
> I don't use those programs so I can only provide general
> instructions about how that is typically done.  I'll
> leave it to someone who can be more specific.

Understanding this would help in simulating exposure changes in an 
editor - to better understand when shooting & interpreting the histogram.

-- 
Paul Furman
www.edgehill.net
www.baynatives.com

all google groups messages filtered due to spam

"DRS" <drs@removethis.ihug.com.au> wrote:
>"Floyd L. Davidson" <floyd@apaflo.com> wrote in message
>news:87ab02ql1h.fld@apaflo.com
>> "DRS" <drs@removethis.ihug.com.au> wrote:
>
>[...]
>
>>> I have always said it changes the indication of exposure.  It is you
>>> who made the false claim that I and others were saying it had
>>> anything to do with changing the actual exposure, which we have
>>> repeatedly denied.
>>
>> *All* *five* *show* *the* *exact* *same* *exposure*.
>
>Yes, how many times do I have to tell you that before you get it?
>
>> Not one of them shows any 1 f/stop difference as you
>> claim.
>
>Yes, they do, in terms of *accuracy*.

You simply do not know how to read a histogram, and until you
learn there is little point in talking to you on any topic
that requires it.

>> The only thing that moves 1 f/stop are the tall peaks in
>> the graph that have *nothing* to do with exposure.  It
>> is well to the left of the right edge, and it is that
>> right edge that indicates exposure.
>
>The right edge moves.

It doesn't.  You are *not* looking at the right edge, you are
looking at a peak that is left of the edge.  The peak moves, the
edge does not.

>>> And because of the different contrast settings the 5 histograms show
>>> the exposure differently.  The exposure hasn't changed but the
>>> accuracy of its representation has.  Which is all that has been
>>> claimed.
>>
>> They *don't* show the *exposure* differently.
>
>Yes, they do.  Everybody can see it except you.

Everyone who knows how to read a histogram can see the same
thing that I do.

>>> None of the 5 histograms indicate overexposure.  What they do
>>> indicate, to different degrees of accuracy, is the room for exposure
>>> compensation.  Only 1 can be the most accurate and it is the -4
>>> histogram.
>>
>> All of them indicate there is no room for any
>> "compensation".  Increasing the camera exposure will
>> result in clipping, and each of those histograms shows
>> that.
>
>No, they don't.  Try looking at what is there.
>
>[...]
>
>>> In this instance that indicates specular highlights, which as has
>>> been noted by several people, may be blown without spoiling the
>>> image.  That is a choice by the photographer.
>>
>> The tall peaks are *not* a "specular highlights", and
>
>I didn't say they were.  Do you ever pay attention?  You can't even follow
>when I'm addressing your argument!

There are *no* specular hightlights in the images shown.

>> You know, logically if what you said made sense the
>> article would have discussed it in some way, but it does
>> not even hint at it.  If changing the contrast displayed
>> a more accurate *exposure* (right edge location), why
>> didn't they point to it?
>
>"What does all this mean?  In order to display the full dynamic range of
>your camera in the histogram displayed on the back, you must set the
>contrast to minimum.  You now can see the same dynamic range in the
>histogram on the camera as you will see it in your RAW processor on your
>computer."

Nice switcheroo, but the article that shows the histograms says
nothing like that.  Here is what it says, in it's entirety:

  "Contrast adjustment

  Adjusting the tone alters the shape of the 'S curve'
  used to map the linear image data captured by the
  sensor into the correct gamma. A lower contrast
  setting maintains more of the original data's dynamic
  range but leads to a flatter looking image. A higher
  contrast setting stretches the grayscale (dark to
  light) of the image and could lead to clipping of both
  shadow detail and highlights. The Neutral Picture
  Style was used for the samples below."

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

Paul Furman <paul-@-edgehill.net> wrote:
>Floyd L. Davidson wrote:
>> Paul Furman <paul-@-edgehill.net> wrote:
>>> Floyd L. Davidson wrote:
>>>> That is exactly the point I *am* making.  WB changes
>>>> the histogram in a useful way.  The Luminous-Landscape
>>>> article did not talk about WB at all.  They discussed
>>>> changing the camera's setting for contrast, and that
>>>> simply does *nothing* useful for the histogram/exposure
>>>> issue. And if you doubt that the contrast setting will not
>>>> change the histogram as stated, *try* *it*.  I gave an step by
>>>> step description of a very easy way to show exactly what
>>>> does and does not happen.  Why argue from supposition when
>>>> you could actually learn something about photography...
>>> I am interested in learning. I tried fiddling with
>>> the camera contrast
>>> settings to compare histograms and the difference was very minor, at
>>> least for the conditions I tried just now.
>
>A second try showed a significant difference.
>
>>> I was thinking of
>>> post-processing where increasing contrast blows highlights & blocks
>>> shadows. Maybe not the very final edge of 100% saturation but contrast
>>> adjustments can make a big difference in what appears to be blown or
>>> blocked.  What you are describing sounds more like a gamma adjustment
>>> than contrast where only the middle part shifts.
>
>Scratch that comment, they both have an effect.
>
>>   "Gamma is equivalent to contrast.
>
>I dunno, maybe your linked definers are thinking of a different context.

I would expect that both Norman Koren and HP do know exactly what
gamma and contrast are.  The context is *exactly* the one we are
discussing.

>Common sense and experience tell me gamma is adjusting the middle-value,
>more like brightness, without changing the the ends.

A generalization, but not wrong.

>Contrast
>adjustments tend to hold the mid-point and use an s curve to raise
>highlights & lower shadows or the inverse.

Not true.  Contrast is the slope of the curve.

>A gamma adjustment curve is a
>fairly simple bowed shape, not an s shape.

Not necessarily.

>Sure a gamma adjustment has
>an effect on contrast but that's a side effect, not the goal. Gamma
>adjustments boost contrast in either the highlights or shadows, not both.

Not necessarily.

>>   This can be observed
>>   in traditional film curves, which are displayed on
>>   logarithmic scales (typically, density (log10(absorbed
>>   light) vs. log10(exposure)). Gamma is the average
>>   slope of this curve (excluding the "toe" and
>>   "shoulder" regions near the ends of the curve), i.e.,
>>   the contrast."
>>      http://www.imatest.com/docs/glossary.html
>>      (The above is a web page owned by Norman Koren.)
>>   "Gamma -- A way of representing the contrast of an
>>   image, shown as the slope of a curve showing tones
>>   from white to black."
>>      http://www.hp.com/united-states/consumer/digital_photography/articles/scanner_glossary.html
>> That might help make things clearer as to why changing
>> contrast does not make the histogram any more or less
>> accurate for exposure.
>> When the histogram indicates precisely the correct
>> exposure, changing the gamma (contrast) moves the curve
>> between black and maximum white values, but it doesn't
>> change the value of either.  Note too that it might
>> spread the histogram out from the center (if the gamma
>> curve is moved by picking a point at its center), or it
>> might move towards ether the right or the left (if the
>> gamma curve is moved from point closer to the ends
>> instead of at the center).
>> In any case, it changes the contrast but if there are
>> image values at the maximum white value they will not be
>> moved.
>
>The maximum white value may be already off the edge so you are talking
>about part of the middle of the curve, which is effected, showing more
>detail with low contrast.

Maximum white values cannot go "off the edge".  They go *to the edge*,
and no higher.  The maximum value does not change, though the number
of pixels that have that value might change.

>>> An interesting related issue I don't understand is how the exposure
>>> slider works in Lightroom or ACR. I don't know how to duplicate that
>>> effect in photoshop with curves, levels, etc. Those all do like you
>>> describe, moving the middle parts of the histogram but there isn't an
>>> easy way I can see to shift the whole exposure. Hmm, the middle slider
>>> on levels comes close but still doesn't match the effect.
>> I don't use those programs so I can only provide
>> general
>> instructions about how that is typically done.  I'll
>> leave it to someone who can be more specific.
>
>Understanding this would help in simulating exposure changes in an
>editor - to better understand when shooting & interpreting the histogram.

Yes, you will certainly find it useful.

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

Porte Rouge <porterougeman@gmail.com> wrote:
>On Oct 8, 6:22�am, fl...@apaflo.com (Floyd L. Davidson) wrote:
>> Paul Furman <pa...@-edgehill.net> wrote:
>> >John Sheehy wrote:
>> >> Paul Furman wrote:
>>
>> >>> OK, the noise is more the reason but posterizing can
>> >>> be a problem in dark areas...
>> >> The only cameras I know of with even a hint of RAW
>> >> posterization are the Pentax K10D, which would profit
>> >> from 13 bits instead of 12 at ISO 100 (not for 200 or
>> >> higher), the Sony A900 also with a need for 13 bits at
>> >> base, and the D3X when in 12-bit mode. �These are only
>> >> on the fringe of posterizing.
>>
>> >>> raising shadows in post for the deepest shadows, and
>> >>> in skies where the color pallet is very
>> >>> limited. Doesn't the noise level follow this same
>> >>> principle? Or is there an unrelated reason for the
>> >>> noise levels paralleling tone counts?
>> >> Any posterization you see in a RAW conversion is most
>> >> likely caused by the math used in the converter, and
>> >> nothing else. �Of course, JPEG compression does some
>> >> posterization of its own, especially if you use too
>> >> much NR and it starts blocking up.
>>
>> >OK, this makes sense, the posterizing issue is not really visible in any
>> >sort of normal exposure. What about Floyd's comment below that the noise
>> >level remains the same but exposing to the right increases the signal so
>> >that overwhelms the noise? That seems to tie the two together in a
>> >comprehensible way. The LL link just makes a lot of sense, it can't be
>> >complete BS.http://www.luminous-landscape.com/tutorials/expose-right.shtml
>>
>> That is an *excellent* article. �It also has a link to
>> another article, titled "Understanding Histograms",
>> which several contributors to this thread could benefit
>> from (particularly the histogram of the moon shot and
>> the high key tree image that are the last two shown at
>> the bottom of the article):
>>
>> �http://www.luminous-landscape.com/tutorials/understanding-series/unde...
>>
>> --
>> Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
>> Ukpeagvik (Barrow, Alaska) � � � � � � �fl...@apaflo.com
>
>Hey, that's the same article you said this about:
>
>"But regardless of that, the cited URL above from
>luminous-landscape is *not* full of good stuff.  They
>miss the point entirely, and provide nothing that is
>actually useful!"

No it is *not* the same article.

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

On Oct 8, 2:36=A0pm, fl...@apaflo.com (Floyd L. Davidson) wrote:
> Porte Rouge <porterouge...@gmail.com> wrote:
> >On Oct 8, 6:22=A0am, fl...@apaflo.com (Floyd L. Davidson) wrote:
> >> Paul Furman <pa...@-edgehill.net> wrote:
> >> >John Sheehy wrote:
> >> >> Paul Furman wrote:
>
> >> >>> OK, the noise is more the reason but posterizing can
> >> >>> be a problem in dark areas...
> >> >> The only cameras I know of with even a hint of RAW
> >> >> posterization are the Pentax K10D, which would profit
> >> >> from 13 bits instead of 12 at ISO 100 (not for 200 or
> >> >> higher), the Sony A900 also with a need for 13 bits at
> >> >> base, and the D3X when in 12-bit mode. =A0These are only
> >> >> on the fringe of posterizing.
>
> >> >>> raising shadows in post for the deepest shadows, and
> >> >>> in skies where the color pallet is very
> >> >>> limited. Doesn't the noise level follow this same
> >> >>> principle? Or is there an unrelated reason for the
> >> >>> noise levels paralleling tone counts?
> >> >> Any posterization you see in a RAW conversion is most
> >> >> likely caused by the math used in the converter, and
> >> >> nothing else. =A0Of course, JPEG compression does some
> >> >> posterization of its own, especially if you use too
> >> >> much NR and it starts blocking up.
>
> >> >OK, this makes sense, the posterizing issue is not really visible in =
any
> >> >sort of normal exposure. What about Floyd's comment below that the no=
ise
> >> >level remains the same but exposing to the right increases the signal=
 so
> >> >that overwhelms the noise? That seems to tie the two together in a
> >> >comprehensible way. The LL link just makes a lot of sense, it can't b=
e
> >> >complete BS.http://www.luminous-landscape.com/tutorials/expose-right.=
shtml
>
> >> That is an *excellent* article. =A0It also has a link to
> >> another article, titled "Understanding Histograms",
> >> which several contributors to this thread could benefit
> >> from (particularly the histogram of the moon shot and
> >> the high key tree image that are the last two shown at
> >> the bottom of the article):
>
> >> =A0http://www.luminous-landscape.com/tutorials/understanding-series/un=
de...
>
> >> --
> >> Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
> >> Ukpeagvik (Barrow, Alaska) =A0 =A0 =A0 =A0 =A0 =A0 =A0fl...@apaflo.com
>
> >Hey, that's the same article you said this about:
>
> >"But regardless of that, the cited URL above from
> >luminous-landscape is *not* full of good stuff. =A0They
> >miss the point entirely, and provide nothing that is
> >actually useful!"
>
> No it is *not* the same article.
>
> --
> Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
> Ukpeagvik (Barrow, Alaska) =A0 =A0 =A0 =A0 =A0 =A0 =A0fl...@apaflo.com

This is the link in both of Paul's posts:

http://www.luminous-landscape.com/tutorials/expose-right.shtml

Porte Rouge <porterougeman@gmail.com> wrote:
>On Oct 8, 2:36�pm, fl...@apaflo.com (Floyd L. Davidson) wrote:
>> Porte Rouge <porterouge...@gmail.com> wrote:
>> >On Oct 8, 6:22�am, fl...@apaflo.com (Floyd L. Davidson) wrote:
>> >> Paul Furman <pa...@-edgehill.net> wrote:
>> >> >John Sheehy wrote:
>> >> >> Paul Furman wrote:
>>
>> >> >>> OK, the noise is more the reason but posterizing can
>> >> >>> be a problem in dark areas...
>> >> >> The only cameras I know of with even a hint of RAW
>> >> >> posterization are the Pentax K10D, which would profit
>> >> >> from 13 bits instead of 12 at ISO 100 (not for 200 or
>> >> >> higher), the Sony A900 also with a need for 13 bits at
>> >> >> base, and the D3X when in 12-bit mode. �These are only
>> >> >> on the fringe of posterizing.
>>
>> >> >>> raising shadows in post for the deepest shadows, and
>> >> >>> in skies where the color pallet is very
>> >> >>> limited. Doesn't the noise level follow this same
>> >> >>> principle? Or is there an unrelated reason for the
>> >> >>> noise levels paralleling tone counts?
>> >> >> Any posterization you see in a RAW conversion is most
>> >> >> likely caused by the math used in the converter, and
>> >> >> nothing else. �Of course, JPEG compression does some
>> >> >> posterization of its own, especially if you use too
>> >> >> much NR and it starts blocking up.
>>
>> >> >OK, this makes sense, the posterizing issue is not really visible in any
>> >> >sort of normal exposure. What about Floyd's comment below that the noise
>> >> >level remains the same but exposing to the right increases the signal so
>> >> >that overwhelms the noise? That seems to tie the two together in a
>> >> >comprehensible way. The LL link just makes a lot of sense, it can't be
>> >> >complete BS.http://www.luminous-landscape.com/tutorials/expose-right.shtml
>>
>> >> That is an *excellent* article. �It also has a link to
>> >> another article, titled "Understanding Histograms",
>> >> which several contributors to this thread could benefit
>> >> from (particularly the histogram of the moon shot and
>> >> the high key tree image that are the last two shown at
>> >> the bottom of the article):
>>
>> >> �http://www.luminous-landscape.com/tutorials/understanding-series/unde...
>>
>> >> --
>> >> Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
>> >> Ukpeagvik (Barrow, Alaska) � � � � � � �fl...@apaflo.com
>>
>> >Hey, that's the same article you said this about:
>>
>> >"But regardless of that, the cited URL above from
>> >luminous-landscape is *not* full of good stuff. �They
>> >miss the point entirely, and provide nothing that is
>> >actually useful!"
>>
>> No it is *not* the same article.
>>
>> --
>> Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
>> Ukpeagvik (Barrow, Alaska) � � � � � � �fl...@apaflo.com
>
>This is the link in both of Paul's posts:
>
>http://www.luminous-landscape.com/tutorials/expose-right.shtml

The article I made that comment about is entirely
different.  It is by Ray Maxwell and is titled "A
Possible Problem with Expose to the Right!  Or Settings
for an Accurate Histogram".

Here is a direct quote from the article I posted,
showing a distinctly different URL than the one above:

 ">>> http://www.luminous-landscape.com/tutorials/right-hista.shtml
  >>    Wow, good stuff. I had to run out and get my camera
  >> and check the
  ...

  But regardless of that, the cited URL above from
  luminous-landscape is *not* full of good stuff.  They"

     Message-ID: <87my45th9g.fld@apaflo.com>
     Date: Mon, 05 Oct 2009 17:58:51 -0800

--
Note that I am not using my usual signature on this
article, because you have quoted it along with the body
of text in every single exchange, which is ridiculous!

Clues wrote:
> On Wed, 07 Oct 2009 17:19:12 -0500, John Sheehy <JPS@no.komm> wrote:
> 
>> Exposure to the right is usually given as advice for RAW shooting.  The 
>> RAW data usually clips well above the level where a JPEG would clip it, 
> 
> Very true, for all those cameras that intentionally do a poor job at the
> RAW to JPG conversion. This is why RAW became so popular. DSLRs are
> inherently poor at this process. In fact it's the very reason that having
> access to the RAW data became so popular. Far too many DSLR owners wanted
> to repair in their resulting images what the DSLR's firmware programmers
> failed to do correctly in the first place. Companies then realized that
> they could turn this into an asset. Not only sell a camera that didn't work
> quite right, bundled with a kit-lens that wouldn't provide images any
> better than a Barbie-Cam, conning them into buying a $5,000-$10,000 lens to
> make their $500 DSLR functional, but now also sell them expensive editing
> software to fix what their cameras weren't doing properly to provide a
> useful image right out of the box.

'Ceptin' the major camera mfg's provide software with the purchaseof the 
camera, and excellent lenses can be had for a mere grand. One or two 
{Nikon} may also try to sell "Pro" RAW converters.

Most in-camera conversion for JPEGs is above very decent, and is 
excellent for daylight/time normal exposures.

-- 
john mcwilliams

Doug McDonald <mcdonald@scs.uiuc.edu.remove.invalid> wrote:
>Floyd L. Davidson wrote:
>
>> Hence if the right edge is set correctly with high
>> contrast or low contrast, either way it is exactly the
>> same exposure and neither is more accurate than the
>> other.
>> You continue to say that low contrast makes it easier
>> to
>> see where the edge is, but that is only true for special
>> cases, and for an equal number of special cases high
>> contrast would make it easier!
>>
>
>In NO CASE would high contrast make it easier ...
>at least on a Canon 30D.
>
>Mr. Davidson: Let me ask again: What is the serial
>number of the Canon 30D you have checked this on.
>
>If you have not done so, SHUT UP.
>
>We admit that you are right if somebody using
>a Canon 30D is willing to allow 2/3 stop more "slop"
>than is really necessary.

It does not appear that you understand how to read a
histogram.

Hmmm... tell me what you make of these two histograms:

  <http://tinyurl.com/493fyp>
  <http://tinyurl.com/4l8lle>

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

Doug McDonald <mcdonald@scs.uiuc.edu.remove.invalid> wrote:
>I have performed tests on my Canon 30D camera to see
>what happens if I expose less. I exposed 1/3 and 2/3
>stops less than before.
>
>At 2/3 stop less than before yes, even at contrast setting zero,
>I do see a teensy bit of space between the top of the red histogram
>and the top of the display. This means that if I'm willing to
>lose 2/3 stop of unclipped data at the bright end, Floyd is "effectively"
>right.
>
>But if I want that extra 2/3 stop, I'm still correct.

You have verified that you can't read a histogram, and
that what I've previously said is true.  Changing
contrast isn't helping you a bit, but WB adjustment
would make your histogram more accurate, as well as make
your preview JPEG image greenish.

Your description suggests that at 0 EC your histogram
was indicating you should be clipping.  The red channel
though, due to WB adjustment, is typcially about 1/2 to
3/4 of an fstop higher in the JPEG than it is in the raw
data.  (Look in the Exif data and to find out what the
red channel multiplier is, and you can calculate exactly
what the fstop value differential is.)

To *correct* the inaccuracy of your histogram you can
adjust the WB to be more greenish.  That will reduce the
red channel in the JPEG to agree with the raw data.

Changing contrast does *not* change the histogram's
representation of exposure, and therefore *cannot* make
the histogram more accurate.  Only WB adjustment will do
that for you.

>I should add that my method works --- I use -4 in the camera,
>use the histogram, and find my raw images are very nicely exposed,
>no clipping (except as desired for specular highlights) and the
>data right up to the clipping level.

All you are doing is misunderstanding the histogram, and
because the WB adjustment gives you 1/2 to 3/4 of an
fstop of leeway, you end up with useful results.  It is
very unlikely that you have the technical expertize to
even determine how close your raw data is to clipping,
never mind being able to see any difference in losing
that amount of dynamic range at the low end of the
exposure range as a result of the inaccurate histogram.

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

"Floyd L. Davidson" <floyd@apaflo.com> wrote in message
news:87pr8xpx5u.fld@apaflo.com
> "DRS" <drs@removethis.ihug.com.au> wrote:

[...]

>> Yes, they do, in terms of *accuracy*.
>
> You simply do not know how to read a histogram, and until you
> learn there is little point in talking to you on any topic
> that requires it.

According to you.  Not according to everybody else.  You maintain you're the 
only one here who understands what's going on but that's not supported by 
the evidence so I'm quite happy to let you drift off in your fantasy world. 

Floyd L. Davidson <floyd@apaflo.com> wrote:
>Doug McDonald <mcdonald@scs.uiuc.edu.remove.invalid> wrote:
>>Floyd L. Davidson wrote:
>>
>>> Hence if the right edge is set correctly with high
>>> contrast or low contrast, either way it is exactly the
>>> same exposure and neither is more accurate than the
>>> other.
>>> You continue to say that low contrast makes it easier
>>> to
>>> see where the edge is, but that is only true for special
>>> cases, and for an equal number of special cases high
>>> contrast would make it easier!
>>>
>>
>>In NO CASE would high contrast make it easier ...
>>at least on a Canon 30D.
>>
>>Mr. Davidson: Let me ask again: What is the serial
>>number of the Canon 30D you have checked this on.
>>
>>If you have not done so, SHUT UP.
>>
>>We admit that you are right if somebody using
>>a Canon 30D is willing to allow 2/3 stop more "slop"
>>than is really necessary.
>
>It does not appear that you understand how to read a
>histogram.
>
>Hmmm... tell me what you make of these two histograms:

You're trying to change the subject.

-- 
Ray Fischer         
rfischer@sonic.net  

"DRS" <drs@removethis.ihug.com.au> wrote:
>"Floyd L. Davidson" <floyd@apaflo.com> wrote in message
>news:87pr8xpx5u.fld@apaflo.com
>> "DRS" <drs@removethis.ihug.com.au> wrote:
>
>[...]
>
>>> Yes, they do, in terms of *accuracy*.
>>
>> You simply do not know how to read a histogram, and until you
>> learn there is little point in talking to you on any topic
>> that requires it.
>
>According to you.  Not according to everybody else.  You maintain you're the
>only one here who understands what's going on but that's not supported by
>the evidence so I'm quite happy to let you drift off in your fantasy world.

The evidence is rather extensive, and nothing I'm saying
is unique.  Everyone who does understand it says
basically the same things...

Here is a tutorial that explains how to get an accurate
histogram.

  <http://www.guillermoluijk.com/tutorial/uniwb/index_en.htm>

As for reading histograms, I don't know of any tutorials
that don't have at least some errors, but this one is
pretty good:

  <http://www.luminous-landscape.com/tutorials/understanding-series/understanding-histograms.shtml>

This tutorial is a pretty good one for learning how to use ETTR:

  <http://www.luminous-landscape.com/tutorials/expose-right.shtml>

If you want a lot of detail, do a google search on Iyla Borg and
"white balance" or "histogram".

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

rfischer@sonic.net (Ray Fischer) wrote:
>Floyd L. Davidson <floyd@apaflo.com> wrote:
>>Doug McDonald <mcdonald@scs.uiuc.edu.remove.invalid> wrote:
>>>Floyd L. Davidson wrote:
>>>
>>>> Hence if the right edge is set correctly with high
>>>> contrast or low contrast, either way it is exactly the
>>>> same exposure and neither is more accurate than the
>>>> other.
>>>> You continue to say that low contrast makes it easier
>>>> to
>>>> see where the edge is, but that is only true for special
>>>> cases, and for an equal number of special cases high
>>>> contrast would make it easier!
>>>>
>>>
>>>In NO CASE would high contrast make it easier ...
>>>at least on a Canon 30D.
>>>
>>>Mr. Davidson: Let me ask again: What is the serial
>>>number of the Canon 30D you have checked this on.
>>>
>>>If you have not done so, SHUT UP.
>>>
>>>We admit that you are right if somebody using
>>>a Canon 30D is willing to allow 2/3 stop more "slop"
>>>than is really necessary.
>>
>>It does not appear that you understand how to read a
>>histogram.
>>
>>Hmmm... tell me what you make of these two histograms:
>
>You're trying to change the subject.

*Narrowing* the subject.

It is exceedingly difficult to discuss histograms with
people who do not understand what a histogram shows and
how to read it.

Until we get all participants on the same sheet when it
comes to how to read a histogram there simply isn't much
point in discussing the other aspects of their use, eh?

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

On Thu, 08 Oct 2009 14:14:55 -0700, John McWilliams <jpmcw@comcast.net>
wrote:

>Clues wrote:
>> On Wed, 07 Oct 2009 17:19:12 -0500, John Sheehy <JPS@no.komm> wrote:
>> 
>>> Exposure to the right is usually given as advice for RAW shooting.  The 
>>> RAW data usually clips well above the level where a JPEG would clip it, 
>> 
>> Very true, for all those cameras that intentionally do a poor job at the
>> RAW to JPG conversion. This is why RAW became so popular. DSLRs are
>> inherently poor at this process. In fact it's the very reason that having
>> access to the RAW data became so popular. Far too many DSLR owners wanted
>> to repair in their resulting images what the DSLR's firmware programmers
>> failed to do correctly in the first place. Companies then realized that
>> they could turn this into an asset. Not only sell a camera that didn't work
>> quite right, bundled with a kit-lens that wouldn't provide images any
>> better than a Barbie-Cam, conning them into buying a $5,000-$10,000 lens to
>> make their $500 DSLR functional, but now also sell them expensive editing
>> software to fix what their cameras weren't doing properly to provide a
>> useful image right out of the box.
>
>'Ceptin' the major camera mfg's provide software with the purchaseof the 
>camera, and excellent lenses can be had for a mere grand. One or two 
>{Nikon} may also try to sell "Pro" RAW converters.
>
>Most in-camera conversion for JPEGs is above very decent, and is 
>excellent for daylight/time normal exposures.

If your camera's resulting JPG file's dynamic range does not closely match
the dynamic range of your RAW data, then there's something obviously very
wrong with your camera, your camera's settings, or you.

(To enlighten the ignorant: There is zero difference in the amount of noise
in a 2 minute exposure in low light and a 1/2000s exposure in bright light.
Photons are photons. If you collect enough to get over the base
noise-threshold then all those parts of the image that are properly exposed
will be noise-free in any image, no matter the initial light levels.)

Kyle D.  <kd@kdsnospam.org> wrote:
>On Thu, 08 Oct 2009 14:14:55 -0700, John McWilliams <jpmcw@comcast.net>
>wrote:
>
>>Clues wrote:
>>> On Wed, 07 Oct 2009 17:19:12 -0500, John Sheehy <JPS@no.komm> wrote:
>>> 
>>>> Exposure to the right is usually given as advice for RAW shooting.  The 
>>>> RAW data usually clips well above the level where a JPEG would clip it, 
>>> 
>>> Very true, for all those cameras that intentionally do a poor job at the
>>> RAW to JPG conversion. This is why RAW became so popular. DSLRs are
>>> inherently poor at this process. In fact it's the very reason that having
>>> access to the RAW data became so popular. Far too many DSLR owners wanted
>>> to repair in their resulting images what the DSLR's firmware programmers
>>> failed to do correctly in the first place. Companies then realized that
>>> they could turn this into an asset. Not only sell a camera that didn't work
>>> quite right, bundled with a kit-lens that wouldn't provide images any
>>> better than a Barbie-Cam, conning them into buying a $5,000-$10,000 lens to
>>> make their $500 DSLR functional, but now also sell them expensive editing
>>> software to fix what their cameras weren't doing properly to provide a
>>> useful image right out of the box.
>>
>>'Ceptin' the major camera mfg's provide software with the purchaseof the 
>>camera, and excellent lenses can be had for a mere grand. One or two 
>>{Nikon} may also try to sell "Pro" RAW converters.
>>
>>Most in-camera conversion for JPEGs is above very decent, and is 
>>excellent for daylight/time normal exposures.
>
>If your camera's resulting JPG file's dynamic range does not closely match
>the dynamic range of your RAW data, then there's something obviously very
>wrong with your camera, your camera's settings, or you.
>
>(To enlighten the ignorant: There is zero difference in the amount of noise
>in a 2 minute exposure in low light and a 1/2000s exposure in bright light.
>Photons are photons. If you collect enough to get over the base
>noise-threshold then all those parts of the image that are properly exposed
>will be noise-free in any image, no matter the initial light levels.)

But electron noise is a function of time and temperature.  The longer
the exposure the more opportunity there is for electrons to party.

-- 
Ray Fischer         
rfischer@sonic.net  

Floyd L. Davidson <floyd@apaflo.com> wrote:
>rfischer@sonic.net (Ray Fischer) wrote:
>>Floyd L. Davidson <floyd@apaflo.com> wrote:
>>>Doug McDonald <mcdonald@scs.uiuc.edu.remove.invalid> wrote:
>>>>Floyd L. Davidson wrote:
>>>>
>>>>> Hence if the right edge is set correctly with high
>>>>> contrast or low contrast, either way it is exactly the
>>>>> same exposure and neither is more accurate than the
>>>>> other.
>>>>> You continue to say that low contrast makes it easier
>>>>> to
>>>>> see where the edge is, but that is only true for special
>>>>> cases, and for an equal number of special cases high
>>>>> contrast would make it easier!
>>>>>
>>>>
>>>>In NO CASE would high contrast make it easier ...
>>>>at least on a Canon 30D.
>>>>
>>>>Mr. Davidson: Let me ask again: What is the serial
>>>>number of the Canon 30D you have checked this on.
>>>>
>>>>If you have not done so, SHUT UP.
>>>>
>>>>We admit that you are right if somebody using
>>>>a Canon 30D is willing to allow 2/3 stop more "slop"
>>>>than is really necessary.
>>>
>>>It does not appear that you understand how to read a
>>>histogram.
>>>
>>>Hmmm... tell me what you make of these two histograms:
>>
>>You're trying to change the subject.
>
>*Narrowing* the subject.
>
>It is exceedingly difficult to discuss histograms with
>people who do not understand what a histogram shows and
>how to read it.

People such as yourself, for example.

-- 
Ray Fischer         
rfischer@sonic.net  

"Floyd L. Davidson" <floyd@apaflo.com> wrote in message
news:87ljjlnohh.fld@apaflo.com
> "DRS" <drs@removethis.ihug.com.au> wrote:

[...]

>> According to you.  Not according to everybody else.  You maintain
>> you're the only one here who understands what's going on but that's
>> not supported by the evidence so I'm quite happy to let you drift
>> off in your fantasy world.
>
> The evidence is rather extensive, and nothing I'm saying
> is unique.  Everyone who does understand it says
> basically the same things...

Except you.  Go read your own tutorials.  I already have. 

"DRS" <drs@removethis.ihug.com.au> wrote:
>"Floyd L. Davidson" <floyd@apaflo.com> wrote in message
>news:87ljjlnohh.fld@apaflo.com
>> "DRS" <drs@removethis.ihug.com.au> wrote:
>
>[...]
>
>>> According to you.  Not according to everybody else.  You maintain
>>> you're the only one here who understands what's going on but that's
>>> not supported by the evidence so I'm quite happy to let you drift
>>> off in your fantasy world.
>>
>> The evidence is rather extensive, and nothing I'm saying
>> is unique.  Everyone who does understand it says
>> basically the same things...
>
>Except you.  Go read your own tutorials.  I already have.

Do it again.  The point is to understand.  You don't.

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

"Floyd L. Davidson" <floyd@apaflo.com> wrote in message
news:878wfkoo6r.fld@apaflo.com
> "DRS" <drs@removethis.ihug.com.au> wrote:
>> "Floyd L. Davidson" <floyd@apaflo.com> wrote in message
>> news:87ljjlnohh.fld@apaflo.com
>>> "DRS" <drs@removethis.ihug.com.au> wrote:
>>
>> [...]
>>
>>>> According to you.  Not according to everybody else.  You maintain
>>>> you're the only one here who understands what's going on but that's
>>>> not supported by the evidence so I'm quite happy to let you drift
>>>> off in your fantasy world.
>>>
>>> The evidence is rather extensive, and nothing I'm saying
>>> is unique.  Everyone who does understand it says
>>> basically the same things...
>>
>> Except you.  Go read your own tutorials.  I already have.
>
> Do it again.  The point is to understand.  You don't.

So you say.  Whatever.  Get a life. 

"DRS" <drs@removethis.ihug.com.au> wrote:
>"Floyd L. Davidson" <floyd@apaflo.com> wrote in message
>news:878wfkoo6r.fld@apaflo.com
>> "DRS" <drs@removethis.ihug.com.au> wrote:
>>> "Floyd L. Davidson" <floyd@apaflo.com> wrote in message
>>> news:87ljjlnohh.fld@apaflo.com
>>>> "DRS" <drs@removethis.ihug.com.au> wrote:
>>>
>>> [...]
>>>
>>>>> According to you.  Not according to everybody else.  You maintain
>>>>> you're the only one here who understands what's going on but that's
>>>>> not supported by the evidence so I'm quite happy to let you drift
>>>>> off in your fantasy world.
>>>>
>>>> The evidence is rather extensive, and nothing I'm saying
>>>> is unique.  Everyone who does understand it says
>>>> basically the same things...
>>>
>>> Except you.  Go read your own tutorials.  I already have.
>>
>> Do it again.  The point is to understand.  You don't.
>
>So you say.  Whatever.  Get a life.

Well, it *is* rather obvious that if you've even looked
at the tutorials all you did was scan them.

In another article I posted URL's to a pair of
histograms and asked what could be determined from them.
So far the only response is from one person who first
says "nothing", and then proceeds to list a few things
(and he did get at least some of it right too!).

  <http://tinyurl.com/493fyp>
  <http://tinyurl.com/4l8lle>

Let's see *you* post an analysis of what they mean.  I
don't think you can.

But I'll also invite your comments on what I have to
say, later.  I'll give everyone who wishes a chance to
do their own analyzing, and then I'll post a lengthy
analysis of each.  I'll also give instructions on how to
generate, with an editor, an image with a very similar
histogram in order to demonstrate what the significant
characteristics of each histogram actually are.  And
(I'll post URL's for the actual images that those
histograms are related to.)

You are welcome to take a shot at it; assuming you
actually do think you know something about histograms,
here's your chance to show it.  My bet is that you won't
even try, because you are well aware that histograms
don't mean much to you.

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

"Floyd L. Davidson" <floyd@apaflo.com> wrote in message
news:873a5sofbn.fld@apaflo.com
> "DRS" <drs@removethis.ihug.com.au> wrote:

[...]

>> So you say.  Whatever.  Get a life.
>
> Well, it *is* rather obvious that if you've even looked
> at the tutorials all you did was scan them.
>
> In another article I posted URL's to a pair of
> histograms and asked what could be determined from them.
> So far the only response is from one person who first
> says "nothing", and then proceeds to list a few things
> (and he did get at least some of it right too!).
>
>  <http://tinyurl.com/493fyp>
>  <http://tinyurl.com/4l8lle>
>
> Let's see *you* post an analysis of what they mean.  I
> don't think you can.

I recognised those histograms from the LL article on histograms without even 
checking.  I remembered the first as the night shot (hence the predominance 
of pixels towards the left) with the moon (hence the smattering of pixels to 
the right).  I remembered the second one as the snow shot, hence the total 
right-shift in the pixels.  Big deal.  I know why they look like they do and 
I know it has nothing whatever to do with the very, very simple point I and 
others have been insisting on and which you alone are denying (and wrongly 
at that since you don't know half as much as you think you do).  As I said, 
get a life, and stop lecturing people on subjects you only half understand. 

"DRS" <drs@removethis.ihug.com.au> wrote:
>"Floyd L. Davidson" <floyd@apaflo.com> wrote in message
>news:873a5sofbn.fld@apaflo.com
>> "DRS" <drs@removethis.ihug.com.au> wrote:
>
>[...]
>
>>> So you say.  Whatever.  Get a life.
>>
>> Well, it *is* rather obvious that if you've even looked
>> at the tutorials all you did was scan them.
>>
>> In another article I posted URL's to a pair of
>> histograms and asked what could be determined from them.
>> So far the only response is from one person who first
>> says "nothing", and then proceeds to list a few things
>> (and he did get at least some of it right too!).
>>
>>  <http://tinyurl.com/493fyp>
>>  <http://tinyurl.com/4l8lle>
>>
>> Let's see *you* post an analysis of what they mean.  I
>> don't think you can.
>
>I recognised those histograms from the LL article on histograms without even
>checking.  I remembered the first as the night shot (hence the predominance
>of pixels towards the left) with the moon (hence the smattering of pixels to
>the right).  I remembered the second one as the snow shot, hence the total
>right-shift in the pixels.  Big deal.  I know why they look like they do and
>I know it has nothing whatever to do with the very, very simple point I and
>others have been insisting on and which you alone are denying (and wrongly
>at that since you don't know half as much as you think you do).  As I said,
>get a life, and stop lecturing people on subjects you only half understand.

Well, that certainly is one point in your favor!  You
actually did recognize what they are.  Of course you are
wrong about them not having anything to do with what we
have been discussing (indeed, they are part of the
tutorial on histograms *because* they relate to what
we've discussed).

Again, I take it the reason *you* cannot provide any
indication of what the significance of those two
particular histograms is, is simply that you don't know.
So much for you claiming to know all there is about
histograms!

And do note that later today I'll post an extensive analysis
of each, showing exactly what can be understood from them.

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

Floyd L. Davidson <floyd@apaflo.com> wrote:
>"DRS" <drs@removethis.ihug.com.au> wrote:
>>"Floyd L. Davidson" <floyd@apaflo.com> wrote in message
>>news:873a5sofbn.fld@apaflo.com
>>> "DRS" <drs@removethis.ihug.com.au> wrote:
>>
>>[...]
>>
>>>> So you say.  Whatever.  Get a life.
>>>
>>> Well, it *is* rather obvious that if you've even looked
>>> at the tutorials all you did was scan them.
>>>
>>> In another article I posted URL's to a pair of
>>> histograms and asked what could be determined from them.
>>> So far the only response is from one person who first
>>> says "nothing", and then proceeds to list a few things
>>> (and he did get at least some of it right too!).
>>>
>>>  <http://tinyurl.com/493fyp>
>>>  <http://tinyurl.com/4l8lle>
>>>
>>> Let's see *you* post an analysis of what they mean.  I
>>> don't think you can.
>>
>>I recognised those histograms from the LL article on histograms without even
>>checking.  I remembered the first as the night shot (hence the predominance
>>of pixels towards the left) with the moon (hence the smattering of pixels to
>>the right).  I remembered the second one as the snow shot, hence the total
>>right-shift in the pixels.  Big deal.  I know why they look like they do and
>>I know it has nothing whatever to do with the very, very simple point I and
>>others have been insisting on and which you alone are denying (and wrongly
>>at that since you don't know half as much as you think you do).  As I said,
>>get a life, and stop lecturing people on subjects you only half understand.
>
>Well, that certainly is one point in your favor!  You
>actually did recognize what they are.  Of course you are
>wrong about them not having anything to do with what we
>have been discussing (indeed, they are part of the
>tutorial on histograms *because* they relate to what
>we've discussed).
>
>Again, I take it the reason *you* cannot provide any
>indication of what the significance of those two

So farall YOU have been able to do is insist that you're right and
everybody else is wrong.  Needless to say, that's never a very
convincing argument.

-- 
Ray Fischer         
rfischer@sonic.net  

On Oct 8, 3:04=A0pm Floyd L. Davidson wrote

"which is ridiculous!"

It is. My apologies. I miss aligned the thread and saw the other link.
Also, I could not see that all the messages in the thread were being
forwarded. Google Groups hides them in the posts.


Porte

A link for your enjoyment.

http://www.rags-int-inc.com/PhotoTechStuff/ETTR/ 

Kyle D. wrote:

> 
> (To enlighten the ignorant: There is zero difference in the amount of noise
> in a 2 minute exposure in low light and a 1/2000s exposure in bright light.
> Photons are photons. If you collect enough to get over the base
> noise-threshold then all those parts of the image that are properly exposed
> will be noise-free in any image, no matter the initial light levels.)


Bzzzzt!
Flat out wrong.

-- 
lsmft

Paul Furman wrote:
>
> An interesting related issue I don't understand is how the exposure slider 
> works in Lightroom or ACR. I don't know how to duplicate that effect in 
> photoshop with curves, levels, etc. Those all do like you describe, moving 
> the middle parts of the histogram but there isn't an easy way I can see to 
> shift the whole exposure. Hmm, the middle slider on levels comes close but 
> still doesn't match the effect.

Image | Adjustments | Exposure... ? 

Porte Rouge wrote:
> Wilba wrote:
>> Porte Rouge wrote:
>>>
>>> I set my exposure to slide the histogram to the right, without clipping
>>> ( when I have time), to capture the most tonal levels . So, now when I
>>> am editing the photos they are over exposed(not clipped). A sunrise is
>>> a good example. The deep colors are washed out. The obvious fix(to me
>>> anyway) in Lightroom or CS4 is to reduce the exposure. Now my question
>>> is, by reducing exposure in post, am I just ending up in the same place
>>> (histogram to the left) as if I had just ignored the histogram when I
>>> was shooting and set the exposure to properly expose the image using
>>> my light meter? I guess in short I am asking if Lightroom or CS4 loses
>>> tonal values when you reduce exposure in editing.
>>
>> Yes, reducing the exposure in Lightroom just puts your histogram back to 
>> the
>> left, so that's a waste of time. To avoid having the deep colours washed
>> out, you need to make use of the full tonal range available in the image. 
>> If
>> you have done a good job of exposing to the right, your highlights will 
>> be
>> pretty much where they need to be. So then all you need to do is raise 
>> the
>> black point (e.g. using the Levels dialog in Photoshop), so that the dark
>> tones in the scene end up as dark tones in the image. If you are using 
>> the
>> Levels dialog in Photoshop, while you drag the black (or white) point
>> slider, press the Alt key to see which pixels are clipped (or blown).
>>
>> (The following relates to my experience with a Canon 450D. YMMV.)
>
> Aha!

:- )  Was that what you actually wanted to know?

>> There are two parts to exposing to the right - levels in the image and
>> saturation of photosites. Whether you are shooting JPEG or raw, the 
>> camera's
>> histogram display shows you the levels in a JPEG produced from the raw 
>> data,
>> so the shape of the histogram curve depends on your settings for 
>> sharpness,
>> contrast, saturation, colour tone, etc.

And white balance, of course.

>> If you are shooting JPEG, all you can do is avoid piling up the histogram 
>> on
>> the right, which prevents gross areas of blown highlights in the image.
>>
>> If you are shooting raw, you can overexpose (beyond the point at which 
>> the
>> histogram curve touches the right boundary), by about two steps and still
>> produce an image from the raw without blown highlights. IOW, the headroom
>> between blown highlights in the JPEG and saturation of the photosites is
>> about two steps (in my experience, with the JPEG settings I use).
>>
>> So if you are bracketing for the best possible exposure, go at least two
>> steps over what the histogram tells you is "correct". The maximum 
>> possible
>> dynamic range occurs at the point where photosites in the highlights 
>> begin
>> to saturate.
>
> What do you mean by steps? Do you mean stops, or steps on the aperture
> or shutter dials?

No, nothing to do with the increments by which the camera's controls change 
the exposure - that's arbitrary. An exposure step is a doubling or halving 
of the amount of light that reaches the sensor. A stop is a step achieved 
via the aperture. Most people also say stop when they mean a step achieved 
via the shutter.

> In everyday raw shooting, you can be quite relaxed about having a small
> spike on the right of the histogram - that's actually a good thing. 

"Wilba" <usenet@CUTTHISimago.com.au> wrote:
>Porte Rouge wrote:
>> Wilba wrote:
>>> Porte Rouge wrote:
>>>>
>>>> I set my exposure to slide the histogram to the right, without clipping
>>>> ( when I have time), to capture the most tonal levels . So, now when I
>>>> am editing the photos they are over exposed(not clipped). A sunrise is
>>>> a good example. The deep colors are washed out. The obvious fix(to me
>>>> anyway) in Lightroom or CS4 is to reduce the exposure. Now my question
>>>> is, by reducing exposure in post, am I just ending up in the same place
>>>> (histogram to the left) as if I had just ignored the histogram when I
>>>> was shooting and set the exposure to properly expose the image using
>>>> my light meter? I guess in short I am asking if Lightroom or CS4 loses
>>>> tonal values when you reduce exposure in editing.
>>>
>>> Yes, reducing the exposure in Lightroom just puts your histogram back to
>>> the
>>> left, so that's a waste of time. To avoid having the deep colours washed
>>> out, you need to make use of the full tonal range available in the image.
>>> If
>>> you have done a good job of exposing to the right, your highlights will
>>> be
>>> pretty much where they need to be. So then all you need to do is raise
>>> the
>>> black point (e.g. using the Levels dialog in Photoshop), so that the dark
>>> tones in the scene end up as dark tones in the image. If you are using
>>> the
>>> Levels dialog in Photoshop, while you drag the black (or white) point
>>> slider, press the Alt key to see which pixels are clipped (or blown).
>>>
>>> (The following relates to my experience with a Canon 450D. YMMV.)
>>
>> Aha!
>
>:- )  Was that what you actually wanted to know?

None of it is correct though.  What do you get, for example, if  you shoot
a image that is mostly an 18% gray card, against a black background?

If you use ETTR to get the most dynamic range, the gray card will show
up as very close to maximum white in the raw data.

  "If you have done a good job of exposing to the right,
  your highlights will be pretty much where they need to
  be. So then all you need to do is raise the black
  point (e.g. using the Levels dialog in Photoshop), so
  that the dark ..."

Obviously that is not true.  The only time it will be
true is when there actually *are* highlights that are
"pretty much" at pur white.  Not all scenes have such
highlights, and therefore not all image data will have
them "pretty much where they need to be".

And that is when you use a raw converter or an editor
for "reducing the exposure in Lightroom just puts your
histogram back to the left.", and it clearly is *not* a
waste of time.

....
>>> So if you are bracketing for the best possible exposure, go at least two
>>> steps over what the histogram tells you is "correct". The maximum
>>> possible
>>> dynamic range occurs at the point where photosites in the highlights
>>> begin
>>> to saturate.
>>
>> What do you mean by steps? Do you mean stops, or steps on the aperture
>> or shutter dials?
>
>No, nothing to do with the increments by which the camera's controls change
>the exposure - that's arbitrary. An exposure step is a doubling or halving
>of the amount of light that reaches the sensor. A stop is a step achieved
>via the aperture. Most people also say stop when they mean a step achieved
>via the shutter.

Yes, they usually say that because in fact it is the
same thing in the context that you have described, it
changes the amount of light reaching the sensor.

And how you can say "nothign to do with the increments
by which the camera's controls change the exposure" and
then describe camera controls changing the
exposure... is amusing.

>> In everyday raw shooting, you can be quite relaxed about having a small
>> spike on the right of the histogram - that's actually a good thing.

It is, assuming you want to clip the highlights.
Otherwise, it's a fatal error, because there is no way
to recover the lost data.  On the other hand, if you
back off on exposure just enough to make sure no
highlights are clipped, the loss of 1/2 to 1 stop of
dynamic range probably will mean absolutely nothing
(given that you won't print out anything that can show
more than 5 or 6 fstops and the camera will almost
certainly be recording 8 or more).

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

"Charles" <charlesschuler@comcast.net> wrote:
>A link for your enjoyment.
>
>http://www.rags-int-inc.com/PhotoTechStuff/ETTR/

Yah gotta admit, that one is great entertainment.  There
multiple whole paragraphs where he gets nothing right!

He's also got two links at the bottom of that page, both
of which are equally a riot to read.

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

Mike Russell wrote:
> This discussion transcended any technical merit long ago, but here's my two
> cents.  
> 
> For both Nikon and Canon the histogram is based on converted channel RGB
> values, not raw sensor values.

By experiment I've confirmed this to be the same of Sony's a900 (and I 
assume other models).  That is to say that the histo changes 
characteristic based on changes of contrast or other settings.

I'd prefer, of course, that when I'm shooting in raw only (as I normally 
do) that the histo be based solely on the raw data.

The real question is, does it, "really" matter?

Excepting specular reflections and source highlights, as long as the 
rest of the histo is inside the post it would not make any difference in 
the end - esp. if the histo is broken out by RGB (as it is on my camera 
and most recent DSLR's (at least the higher end ones)).

In the end one must use ones metering skills to complement histo 
observations, esp. as the former is pre-shot and the later is after the 
fact.

For shooting in changing light conditions, the meter trumps the histo.

Wilba wrote:
> Porte Rouge wrote:
>> Wilba wrote:
>>> Porte Rouge wrote:
>>>> I set my exposure to slide the histogram to the right, without clipping
>>>> ( when I have time), to capture the most tonal levels . So, now when I
>>>> am editing the photos they are over exposed(not clipped). A sunrise is
>>>> a good example. The deep colors are washed out. The obvious fix(to me
>>>> anyway) in Lightroom or CS4 is to reduce the exposure. Now my question
>>>> is, by reducing exposure in post, am I just ending up in the same place
>>>> (histogram to the left) as if I had just ignored the histogram when I
>>>> was shooting and set the exposure to properly expose the image using
>>>> my light meter? I guess in short I am asking if Lightroom or CS4 loses
>>>> tonal values when you reduce exposure in editing.
>>> Yes, reducing the exposure in Lightroom just puts your histogram back to 
>>> the
>>> left, so that's a waste of time. To avoid having the deep colours washed
>>> out, you need to make use of the full tonal range available in the image. 
>>> If
>>> you have done a good job of exposing to the right, your highlights will 
>>> be
>>> pretty much where they need to be. So then all you need to do is raise 
>>> the
>>> black point (e.g. using the Levels dialog in Photoshop), so that the dark
>>> tones in the scene end up as dark tones in the image. If you are using 
>>> the
>>> Levels dialog in Photoshop, while you drag the black (or white) point
>>> slider, press the Alt key to see which pixels are clipped (or blown).
>>>
>>> (The following relates to my experience with a Canon 450D. YMMV.)
>> Aha!
> 
> :- )  Was that what you actually wanted to know?
> 
>>> There are two parts to exposing to the right - levels in the image and
>>> saturation of photosites. Whether you are shooting JPEG or raw, the 
>>> camera's
>>> histogram display shows you the levels in a JPEG produced from the raw 
>>> data,
>>> so the shape of the histogram curve depends on your settings for 
>>> sharpness,
>>> contrast, saturation, colour tone, etc.
> 
> And white balance, of course.
> 
>>> If you are shooting JPEG, all you can do is avoid piling up the histogram 
>>> on
>>> the right, which prevents gross areas of blown highlights in the image.
>>>
>>> If you are shooting raw, you can overexpose (beyond the point at which 
>>> the
>>> histogram curve touches the right boundary), by about two steps and still
>>> produce an image from the raw without blown highlights. IOW, the headroom
>>> between blown highlights in the JPEG and saturation of the photosites is
>>> about two steps (in my experience, with the JPEG settings I use).
>>>
>>> So if you are bracketing for the best possible exposure, go at least two
>>> steps over what the histogram tells you is "correct". The maximum 
>>> possible
>>> dynamic range occurs at the point where photosites in the highlights 
>>> begin
>>> to saturate.
>> What do you mean by steps? Do you mean stops, or steps on the aperture
>> or shutter dials?
> 
> No, nothing to do with the increments by which the camera's controls change 
> the exposure - that's arbitrary. An exposure step is a doubling or halving 
> of the amount of light that reaches the sensor. A stop is a step achieved 
> via the aperture. Most people also say stop when they mean a step achieved 
> via the shutter.

The original meaning of a stop comes form a"stop" plate with varied 
sized holes in it.  Today that would be the "f-stop".

Otherwise a stop is a stop no matter how it is achieved.  This is 
inherent in reciprocity.

Whether aperture, shutter speed, filters, light levels (control of flash 
or constant lighting by any means) it's a "stop" (or fraction thereof).

Charles wrote:
> A link for your enjoyment.
> 
> http://www.rags-int-inc.com/PhotoTechStuff/ETTR/ 
> 
> 

While forcefully written and mostly (which means more than 50%) right, 
it contains vague or erroneous claims of source information.

For example:  Claim:  "The photographic design point is, has been, and 
will continue to be based on the middle gray tone.   This is the basis 
of the sunny daylight f/16 rule.   It is the reference point for all 
exposure metering systems.   It is also ingrained into the CIE color 
matching functions and all color order systems. "

CIE 1931 makes no reference to sunny-16 nor to grey as control point 
(other than to say that grey is just another version of white).

Paul Furman <paul-@-edgehill.net> wrote in
news:hajq5b$nt5$1@news.eternal-september.org: 

> OK, this makes sense, the posterizing issue is not really visible in
> any sort of normal exposure.

It shouldn't be visible in any kind of exposure.  My comments about the 
limit of the value of RAW bit depth or the number of RAW levels is based 
on torturous tests!

> What about Floyd's comment below that the
> noise level remains the same but exposing to the right increases the
> signal so that overwhelms the noise?

The read noise (including any dark current) stays the same, in an 
absolute sense.  In a relative sense, it changes.  For shot noise, it 
changes in both an absolute sense *and* a relative sense. 

> That seems to tie the two
> together in a comprehensible way. The LL link just makes a lot of
> sense, it can't be complete BS.
> http://www.luminous-landscape.com/tutorials/expose-right.shtml 

Well, the reasons given for the benefit are not correct.  You could take 
one shot with normal exposure, and one with +1 EC, now using the top RAW 
stop, and the benefit would still be there if you quantized the top stop 
to 300 levels, instead of ~8000.  According to my calculations and 
emulations, no current DSLR needs more than 300 levels for the top stop 
(some older models with few, large pixels may need about 325).

Mike Russell wrote:
> On Mon, 05 Oct 2009 15:23:57 -0800, Floyd L. Davidson wrote:
> 
> [re film's "expose for shadows", digital's "expose for the highlights"] 
>> Actually, since film is a negative, the two are in fact
>> actually the same.  Expose for the brightest range of the
>> *recording* *mechanism*.
>>
>> That just happens to be the dark areas of a scene with
>> film (where the negative is clear) and the bright areas
>> of a scene with an electronic sensor (the highest
>> voltage output).
> 
> No - both refer to areas of the scene.  The full rule of thumb for film is
> "Expose for the shadows.  Develop for the highlights".  Exposing for the
> shadows establishes the area of minimum negative density, and development
> has a much greater effect on the highlights than the shadows.

As I've mentioned before in this thread, digital sensors resemble slide 
film, not negative.

For slide film, the "rule" has always been to expose for the highlights, 
not the shadows.  Development (except for push/pull) is cast more or 
less in concrete.

Wilba wrote:
> Paul Furman wrote:
> 
>> An interesting related issue I don't understand is how the exposure slider 
>> works in Lightroom or ACR. I don't know how to duplicate that effect in 
>> photoshop with curves, levels, etc. Those all do like you describe, moving 
>> the middle parts of the histogram but there isn't an easy way I can see to 
>> shift the whole exposure. Hmm, the middle slider on levels comes close but 
>> still doesn't match the effect.
> 
> Image | Adjustments | Exposure... ? 

Hmph, CS1 doesn't have that.

-- 
Paul Furman
www.edgehill.net
www.baynatives.com

all google groups messages filtered due to spam

On Oct 10, 1:57=A0am, fl...@apaflo.com (Floyd L. Davidson) wrote:

> And how you can say "nothign to do with the increments
> by which the camera's controls change the exposure" and
> then describe camera controls changing the
> exposure... is amusing.

I think he meant the increments on the controls are arbitrary(1/3,
1/2, or 1 stop for each click on the dials.

Porte Rouge <porterougeman@gmail.com> wrote:
>On Oct 10, 1:57�am, fl...@apaflo.com (Floyd L. Davidson) wrote:
>
>> And how you can say "nothign to do with the increments
>> by which the camera's controls change the exposure" and
>> then describe camera controls changing the
>> exposure... is amusing.
>
>I think he meant the increments on the controls are arbitrary(1/3,
>1/2, or 1 stop for each click on the dials.

But that does happen to be *exactly* where the term "stop" came
from.

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

> >I think he meant the increments on the controls are arbitrary(1/3,
> >1/2, or 1 stop for each click on the dials.
>
> But that does happen to be *exactly* where the term "stop" came
> from.

I'll let you and Alan figure out where "stop" came from.

The amount of change in exposure per click on the dials on my DSLR is
arbitrary, I choose how much I want.

Porte Rouge wrote:
>
>>> I think he meant the increments on the controls are arbitrary(1/3,
>>> 1/2, or 1 stop for each click on the dials.
>>
>> But that does happen to be *exactly* where the term "stop" came
>> from.
>
> I'll let you and Alan figure out where "stop" came from.
>
> The amount of change in exposure per click on the dials on my DSLR
> is arbitrary, I choose how much I want.

Right. And those increments have nothing to do with what I was talking 
about - you get that, don't you?  :- ) 

In rec.photo.digital.slr-systems Paul Furman <paul-@-edgehill.net> wrote:

> What about saturation? Reducing saturation seems to give more detail to 
> the edges also.

That could be a side effect of chromatic aberration. Do you notice it
when there's no chromatic aberration?

-- 
Chris Malcolm

Paul Furman wrote:
> OK, this makes sense, the posterizing issue is not really visible in any 
> sort of normal exposure. What about Floyd's comment below that the noise 
> level remains the same but exposing to the right increases the signal so 
> that overwhelms the noise? That seems to tie the two together in a 
> comprehensible way.

Look at it this way: Your RAW image will have the same amount of noise, 
regardless of the exposure. But exposing to the right will lift the 
shadow levels up higher, relative to the noise. When you process the RAW 
image on your PC, you'll lower the brightness levels back down, thus 
lowering the absolute noise levels with them.
More technically, you're maximising the signal-to-noise ratio.


-- 
    W
  . | ,. w ,   "Some people are alive only because
   \|/  \|/     it is illegal to kill them."    Perna condita delenda est
---^----^---------------------------------------------------------------