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Re: Litho Film


  • From: "Paul A. Lehman" <palehman@xxxxxxxxxxxxx>
  • Subject: Re: Litho Film
  • Date: Mon, 18 May 1998 15:49:41 -0500

Joel Alpers wrote:

> You're right on the 1-stop downrating, on the kits I've seen.
> 
> It probably is better on slower films, but I don't know if that's a
> requirement. Paul??

Its truly a function of what film and the ASA you use,
and how far you develop it in the first step.

The idea is to expose/develop "half" the silver in the
first step, remove it in the bleach, then re-expose the
remaining silver. If you underexpose, there is too much
silver left over and the reversal picture looks fogged
and dark, if overdeveloped the reversal will be too
thin, etc. Theoretically, once you have bleached the
film, all the remaining steps can be done in a fully
lit room. One source claimed that if done right, fixing
is not necessary since all of the silver has been
consumed through the second exposure/developing step (I
would still fix though). This should also apply if you
are using a chemically induced second exposure step
rather than light.

Shoot a couple of rolls of film like you are doing a
Zone system setup. First develop each at N-1, N and
N+1, etc. The second exposure and development should
not need adjusting as they should go to completeness.
Find the image that looks right to you and that sets
the exposure and 1st developing parameters for future
runs.

Since reversal film processing was originally designed
when film was silver rich (ah, the good old days, I'd
kill for some fresh Super-XX) the original formulas
(such as in your Darkroom Cookbook) may suggest times
and exposures that may not work well with modern films
that have only a fraction of the silver (thus the need
for the test rolls mentioned above).

I know, I know, you wanted a simple "yes" "no" answer,
sorry about that.
;>)

Paul A. Lehman