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Re: development for alt-process; SBRs



shannon stoney wrote:
> ...  Like, if you had a
> very dense negative with the right range, could you just expose the paper
> longer?

and Carl Weese wrote:
> ... In my example of snow scenes, what's important is
> that the limited range is placed up in the highlight and midtone areas of
> the film curve. The same interval lower on the curve could make a
> dark-to-middle-gray range, but that wouldn't be convincing as snow in the
> final print. 

Keeping what Carl said in mind, I have found many snow scenes
(especially with overcast light) to require N+3 development adjustment. 
I made some recently at N+2 (thinking that to be OK) and was supprised
to find not enough separation.  (I should have metered more carefully,
the eye is fooled easily in such situations.)  When in the desert with
bright sun I have had the need for N+4 and even N+5 to get the texture
from such "flat" conditions.

However, an alternative to getting the separation in upper values by
increasing film development is to get the separation by having a better
discrimination of the upper values as can be accomplished with a 100%
palladium print and a good paper choice.  The result is that the
apparent range appears correct even though the actual range isn't.

Exposing the Pt/Pd coating longer can have other ramifications.  One
being that the contrast is lowered.  This could work against what is to
be retrieved from a dense negative and may produce muddy lower tones. 
But if there are no large or important dark areas in the image and
Carl's caution is headed, a long exposure can provide for a successful
print.  I had this type of situation with some of my folded axis work,
where the densities from two negatives are added.  Many of the prints
required very long exposure, one being in excess of three hours (plus
additional exposure for burning).  For refference printing only one of
the negatives used an exposure of 5.5 minutes (keep in mind that
different coating chemistry was used).  This image is #00330-3+4, the
third of the folded axis examples on my web site.

Concerning overexposure, Pt/Pd material "looks" at much more of the
range of a negative (tri-X film, others may differ or not) and thus has
less leeway.  However a negative (tri-X) can still hold a greater range
than the Pt/Pd materials are capable of, meaning that some over exposure
or dense portions can be utilized.  It is recommended that enough
exposure is given so that the toe portion of the negative can be
effectively discarded so that all of the range including dark values are
on the "straight" line portion (gives better separation in the dark
values).  ("straight" is a relative term, but the meaning should be
understood)

Another concern with dense negatives is that the upper value local
contrast may be reduced by processing flaws.  If planning a dense
negative it may be a good idea to provide good continuous (but random)
agitation during the entire film development and make sure to have
enough (volume) of developer so that exhaustion does not become a
factor.

-- 
Jeffrey D. Mathias
http://home.att.net/~jeffrey.d.mathias/