Re: shadow density in zone III

----- Original Message -----
From: "Dennis Purdy" <dennispurdy@earthlink.net>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Thursday, September 29, 2005 8:40 AM
Subject: Re: shadow density in zone III

> Hello List, I am a lurker named Dennis and this is my
> first post,
>
> This zone system discussion has been interesting and my
> experience with it was being taught in 1974 by Glen
> Fishback who wrote the original handbook for the Pentax
> spot meter and modified the AA zone system by reducing the
> number of zones to be concerned with. It is the only
> system of exposure calculation I have ever used though it
> has become simplified to squinting my eyes to find the
> darks in previsualization and metering to make sure I get
> enough exposure there. Then reading the whites that I
> want detail in and considering how much of a problem it
> will be to print it.
>
> The thing that has frustrated me with silver paper is that
> since the improvement of AGFA in the early 80s I have
> never been satisfied with the quality or character of
> silver gel printing even with the chlorobromides. To
> this day I seem forced to make prints very contrasty with
> deep blacks to get the paper to look it's best and long
> scale prints are always rather flat and ugly.. I know
> there are people who have figured out how to make
> beautiful long scale silver prints but in general it is
> too frustrating for me. I think the thing that annoys me
> most is the brightened paper.
>
> Which brings me to my question. I notice that all the
> zone system talk here references silver paper.
> Considering this is an alt list, has anyone figured out
> what are the best low end densities to print with great
> detail on a platinum print? PL/PT is my printing method
> since the 80s and the precision of my metering/processing
> technique has bee reduced to "give it a hell of a lot of
> exposure and processing" so that I can print to black
> without using a lot of inhibiter. What is the ideal
> negative density for Zone 2 and zone 9 in pl/pd printing.
>
> thanks
>
  I think there is another factor here. Some alternative
processes, Platinum being one of them, are to some degree
self-masking. This is because exposure to light also tends
to desensitize the sensitive coating. The result is a long
shoulder which tends to reproduce shadows with low contrast.
POP has a similar, but more exagerated, characteistic. As a
result a negative will never look the same on normal
silver-gelatin paper as it does on either POP or Platinum.
This is a matter of curve _shape_ not slope or extent. In
general, glossy silver-gelatin paper can reproduce a longer
brightness range than any alternative process. That is, Dmax
is greater (around 2.2 for modern papers) and the
reflectivity of the paper white is greater. This last is
partly due to the sizing under the emulsion which is either
Barium sulfate (fiber paper) or Titanium dioxide (RC papers)
which are among the most reflective materials known for
diffuse reflection.

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