Re: zone system and large format film

----- Original Message -----
From: "Shannon Stoney" <sstoney@pdq.net>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Thursday, September 29, 2005 7:35 AM
Subject: Re: zone system and large format film

> >Well, I'm getting up my nerve to ask a sort of non alt
> >question--but at least it does deal with large negatives!
>>
>>When you all are out in the field, do you generally place
>>your shadows on Zone III and highlights on Zone VII or
>>Zone VIII?? What happened in between Adams' zone system
>>and Carson Graves et al? It seems that people have
>>migrated to a Zone VII highlight, and contracted the zones
>>to fewer. Minor White in his book from the 60's says that
>>paper changed and got more compressed and that is why the
>>change. Is this true? Techiegeeks, PLEASE enlighten
>>me, especially those who used papers from early on
>>(30's-60's) until now....Condenser enlargers, VC paper, #2
>>filter as normal.
>>Chris
>
>
> This is interesting. I didn't know that there had been a
> change in the way people conceive of the zone system
> scale. I always place the highlights in zone VII and the
> shadows in zone III. Specular highlights I guess are in
> zone VIII or IX.
>
> I have used Azo papers in the past, which were invented in
> the thirties I guess . The paper scale for Azo is about
> 1.4, a longer scale than say modern Ilford paper. Azo
> papers are contact printed.
>
> I use a condenser enlarger sometimes, and with it, modern
> paper has a short scale, about .90. The diffusion
> enlarger that I use has a scale of about 1.3, on Agfa
> multicontrast classic papers with Agfa Neutol Warm Tone.
>
> The fact that the paper scale got shorter between the
> thirties (Azo) and the sixties (Ilford) doesn't change how
> I place the shadows relative to the highlights. I just
> develop the film longer for longer scale papers. I use
> the BTZS system, and I test the paper and the film to make
> sure they match.
>
> Hope this makes sense.
>
> --shannon
>
>
     Be careful of the term paper scale. If you mean the
range of densities neither old data sheets or old prints
show this to be true. If you mean contrast its likely that
there is a difference. Paper contrast is the range of
exposure needed to go from paper white to Dmax and is
designed to match negative density ranges given certain
printing conditions. Kodak published both contrast and speed
values for its papers going back at least to 1940. Earlier
data sheets state contrast as a log exposure value called
exposure scale, current data sheets show an "R" or Range
value, which is the log value rounded off and multiplied by
100. The 1943 values are given as a ratio which I have
translated to log values.

Azo, Glossy
Grade 0 1 2 3 4 5
1943 1.50 1.30 1.15 0.90 0.74 0.56
1952 1.50 1.32 1.15 0.90 0.75 0.60
1995 ---- 1.30 1.10 0.90 ---- ----

   The difference in Grade-2 is probably a rounding error
since R values are given to only two decimal places.
   Dmax of the paper remained about Log 1.8 for all
examples.
   It is difficult to compare the D-LogE curves because the
modern curve is drawn on a different scale, but the Grade-2
curve appears to have a less extended toe, i.e., more
contrast in the highlights. This may be no more than an
artifact of the measurement method.
   The curves for the 1940's and 1950's papers in comparison
to enlarging papers of the time indicate the curve shape is
essentially identical and contrast values for each grade not
much different.
   The point of this is that Azo was never a "magic" paper
with characteristics significantly different from others.
Because modern enlarging papers have higher Dmax and contain
brighteners their effective range of visual brightness
should be somewhat greater.
   I have seen BTW the really wonderful prints made by
Micheal and Paula. I can not fault them but I am far from
convinced that they could not be duplicated on other paper.
   Contact prints often look better than enlargements simply
because they are smaller. Also they eliminate flare, which
in printing (from negatives) tends to spread out shadows
making the image look muddy. This is BTW why diffusion on an
enlarger looks different than the same diffusion on the
camera and is often not satisfactory.
   As a last remark I commend to those who are really
interested in sensitometry and tone reproduction the work of
Loyd A. Jones. Jones did research into tone reproduction for
Kodak Labs over a long period, probably 30 years. Some of
his work is published in condensed form in various standard
texts like the famous _Theory of the Photographic Process_
C.E.K.Mees (get the "revised edition" if possible). The
original work is published in various scientific and
technical journals, much of it in the _Journal of the
Franklin Institute_. Mees has an extensive bibliography. I
find Jones' approach much more understandable and rational
than the Zone System although both cover much the same
material and have as their objective the photographer's
ability to get good and predictable tone reproduction. Most
of this material is applicable to alternative printing
processes as well as to silver-gelatin.

---
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix.netcom.com