Digital BW, The Print

Todd,

I just want to point out that dynamic range in photography is generally
discussed along with contrast. You don't need to get everything into a
single value.

Austin is discussing an interesting relationship but it is not the
relationship commonly called dynamic range in photography, i.e. the ratio of
lightest and darkest which is frequently quantified as the density range. I
believe that the property he is discussing is of interest but I don't see it
as a new or expanded definition of this ratio.

What you mention below seems to be simply an issue of contrast. The response
to exposure may become steeper or shallower depending upon the grade of the
paper but once the print is a done deal the original grade is no longer a
contributing factor. You are right and contrast is independent of density
range and of what is commonly called dynamic range.

Phil Davis discussed this at great length in "Beyond the Zone System" with
lots of curves showing how Scene Brightness Range maps to the negative by
way of the film's exposure response curve and how the negatives density
range maps to the print by way of the paper's exposure response curve.

It is interesting that he manages to get through 200+ pages of photographic
sensitometry and never even uses the term dynamic range.

I have to agree with Roy that it serves little purpose to redefine dynamic
range as something different than how it is commonly used in photography. I
think that we would be better served at this point if there was a different
term for the relationship Austin is describing. I know Austin will not like
this but if the term dynamic range has already been appropriated, rightly or
wrongly, trying to switch just adds to the confusion.

Martin

P.S. Since when do prints have pixels? <G>

----- Original Message -----
From: "Todd Flashner" <tflash@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Friday, April 05, 2002 3:16 PM
Subject: Re: [Digital BW] Thoughts about Imaging


> Roy,
>
> I'm sensing that some of us have locked horns when we are probably more in
> agreement than out of agreement. Perhaps if we all surrender a little
ground
> we can turn this back into a useful discussion.
>
> Is it possible that *some* people used the term dynamic range to describe
> something one step more complex than density range? I think behind
Austin's
> absolutist rhetoric that is what he's saying.
>
> Working with my sense of logic, which doesn't prove anything, let's look
at
> the bigger picture. Lets consider a common situation we as photographers
> experience. Say through careful exposure and development we have a
negative
> with a beautiful delicate distribution of tones throughout it's useful
> range. It would perfectly fit all it's tones on a given grade 2 paper.
Let's
> say that print's density range would be 2 units. If we could measure the
> print on a pixel by pixel basis it would yield a perfect distribution of
> tones in a histogram, right to the ends with no clipping. We could then
> print that negative on a grade 3 paper, which may also yield a density
range
> of 2 units, but we "clip" tones from the image on both ends due to
increased
> contrast. It's histogram shows the clipping accordingly. We could even
> extend the scenario to where we keep the print on grade 3 paper, but dodge
> the shadows and burn the highlights, thus maintaining a higher internal
> contrast through the midtones, without clipping the ends. It's density
range
> is still 2 units, and it's histogram looks more like the grade 2 print, at
> least at the ends.
>
> Something *is* different in each of these prints, but it is not the
density
> range. Is it possible that some people would say that the grade 2 print
had
> a greater dynamic range than the straight grade 3 print, and that the
> manipulated grade 3 print might have had the greatest dynamic range of the
> three? If not dynamic range, what would be that term?
>
> Todd
>
>
>
>
>
> > --- In DigitalBlackandWhiteThePrint@y..., "Austin Franklin"
<darkroom@i...>
> > wrote:
> >> Roy,
> >>
> >>> So, how can we here is our niche, talk about coming up with a new
idea,
> >>> new concept of what "dynamic range" means?
> >>
> >> No one is coming up with any new concepts...  "We" are merely pointing
out
> >> that the term has been "misapplied" in this "field", and that it
attributes
> >> a different property than, though is loosely related to, density range.
> >
> > Austin,
> >
> > I think Todd's "lost in the trees at points and loose sight of the
woods"
> > quote is right on.
> >
> >>
> >>> We a just a part of a large
> >>> community of imaging that long time ago has defined and has commonly
used
> >>> this term to mean sometime very specific.
> >>
> >> Can you show evidence of this?
> >
> > I think the Ansel Adams book and the Real World Scanning references were
> > pretty relevant.  I'm glad to see you have read the scanning book.  You
> > quoted one sentence that contained "dynamic range describes the actual
> > limits of how many tones the scanner can really differentiate from light
to
> > dark".  You seem to be associating:  dynamic range <--> how many tones,
> > when I think the real association is:  dynamic range <--> actual limits.
> > Reading just this one sentence might be a little ambiguous, but read the
whole
> > paragraph.  Immediate following this sentence is the staircase example:
> > dynamic range <--> height of staircase,  bit depth <--> number of steps.
> > Later on he compares a scanner with "enormous dynamic range but only
> > 256 steps" and a scanner with "lots of tiny steps and tiny dynamic
range".
> > There's no way to interpret these two examples to mean dynamic range
> > is a measure of number of tones or steps!
> > Do you wish to claim that this book and the three guys who wrote
> > it are wrong and misuse and misdefine the term??
> >
> > If you look at the Adam's book there's a diagram that explicitly shows
> > "dynamic range".  He's talking about exposure and shows very clearly
> > dynamic range going from about Zone I to Zone IX saying its the "useful"
> > range of light values in the scene.  He even mentions how this dynamic
> > range of light values maps directly into the range of "useful" densities
on
> > the negative.  Would you like to claim he's all wrong, too?
> >
> > Please consider your position as it relates to these references.  These
> > are both very explicit references to dynamic range as it relates to
imaging.
> >
> > Regards,
> > Roy
> >
> >
> >>
> > ... monitor stuff snipped
> >
> >>
> >> Austin
>
>
>
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