From: Scott Wainer (email@example.com)
Date: 04/08/03-05:36:26 PM Z
I can almost live with whatever film speed I get. I thought that it might be
about 1/2 - 1 stop less, I just didn't expect it to be 3-4 stops less than
what the manufacturer rated it at. If that is truly the case then I will
just go back to shooting Pan F+ (ASA/ISO 50) which gives me an EI of 32 with
the same setup, chemistry, and processing.
What I don't get is that all of the published data shows a higher EI than
what I am getting; some times higher than what the manufacturer rated it at.
Could my setup be that far off that I am loosing 3-4 stops?
----- Original Message -----
From: "Greg Schmitz" <firstname.lastname@example.org>
Sent: Tuesday, April 08, 2003 7:13 PM
Subject: Re: Film Speed and Negative Development
> I don't want to rain on your parade, but it has been my experience
> that it is almost impossible to raise the true speed of any film - no
> matter what. I have exposed and developed hundreds, perhaps thousands
> of rolls of test film. In reality what is usually meant by an
> "increase in speed" is really an increase in contrast. The point at
> which the films curve begins to pivot upward does not change, it just
> gets steeper. I have seen minimal increases in true film speed with a
> few special additives, pre/post-exposure, and exposing film to certain
> gas fumes.
> Depending on what your criteria are for your negative you may well
> find that your final results are lower than that stated by the
> manufacturer. I base my film tests directly on the requirements I
> have for a given type of positive and frequently rate the films' speed
> differently for the process that I am using to produce the final
> positive. My standard exposure for Tri-X 135, for example, is usually
> either 200 or 320.
> -greg schmitz <email@example.com>
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