Archived posting to the Leica Users Group, 1999/02/21

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Subject: Re: [Leica] B&W film speed
From: "Joe Stephenson" <>
Date: Sun, 21 Feb 1999 16:42:34 -0700

Dear Gib,
Except for T-MAX 100, I expose all B&W ASA 100 films at 100 and never
compensate with development. I may fudge the meter reading a bit if I think
it's needed. But I feel development compensation is most useful with sheet
film where it's easy to process each sheet, or groups of sheets as desired.
I really don't know anyone who pushes or pulls when developing film, except
in unusual situations.
Joe Stephenson

- -----Original Message-----
From: Gib Robinson <>
To: Leica List <>
Date: Sunday, February 21, 1999 8:35 AM
Subject: [Leica] B&W film speed

>To LUGers with darkrooms:
>Recently Nathan Wajsman listed the ISO/EI speeds he uses to expose various
>B&W emulsions (Delta 100 at EI=80, etc.). The impression I get from his
>and from other posts on the topic of film speed is that he and others of
>with darkrooms generally shoot a given B&W film at the SAME ISO/EI speed
>irrespective of lighting conditions. Is that true? If so, WHY? (As my
>daughter so frequently says these days).
>Those of us using commercial labs may not have the option of varying
>development times, but I assume those of you with darkrooms DO change BOTH
>exposure times and development times to control contrast. For example, for
>PAN films in high contrasting situations (rodeo riders in bright sun at
>noon), I would be inclined to over expose (effectively increase the film's
>ISO) to preserve shadow detail and under develop in the darkroom to control
>high lights. That way, I would be likely to get a smoother, more printable
>negative to work with.
>So, if I have access to a darkroom and I'm in control of the films
>development process, I don't just assign one ISO/EI number to an emulsion.
>may have a base number I start from under "normal" lighting conditions, but
>I vary that number according to the specific lighting conditions I face
>I shoot a roll and the specific sort of results I want with respect to
>contrast range on the negative. Am I making sense here? Is that how you
>folks with darkrooms work or do you stick with one film speed for each