Re: Re. Increasing Film sensitivity

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From: Bob Kiss (bobkiss@caribsurf.com)
Date: 12/27/01-08:05:10 PM Z


DEAR JOHN,
    I have never seen a conventional film produce an image without
development. There is no such thing as a sensitivity "built into a film
{only} at its manufacture". ALL aspects of a film are related to a
film/developer combination. Yes, of course, some films are faster, finer
grain, etc due to manufacturing but all of those properties are manifested
by film/developer/developing condition combinations...not the film alone.
Manufacturing creates tendencies, development determines the extent to which
they are manifested...very much like the ongoing debate about the effects of
genetics and environment on personality traits and abilities.
    I am not talking about the ANSI standard speed which results from some
very specific exposure and processing conditions (which hardly ever resemble
the practical conditions of use), I am talking about practical usable speed
for each users conditions.
And Diafine or the newer version (I forget the name) for T-max films does
yield a higher "practical" speed/sensitivity. The first thing I learned at
RIT in 1969 was NOT to believe any manufacturers but to test under our own
working conditions...and test we did until I had sensi-strips and practical
shooting tests on the brain. It was and still is amazing just how far off
most manufacturers claims are...but of course they can claim that it is due
to "my" working conditions. "Not all that glistens is gold..."
                        CHEERS!
                            BOB
----- Original Message -----
From: <Grafist@aol.com>
To: <alt-photo-process-l@usask.ca>
Sent: Wednesday, December 19, 2001 4:35 PM
Subject: Re. Increasing Film sensitivity

> Re the recent question on the possibility of increasing film sensitivity
> after exposure.........After some reflection I would submit that the
> "sensitivity" of a film to light is built into its emulsion at
manufacture.
> After exposure the sensitivity of the film would have been all used up, as
it
> were. The chemical structure of the silver halides has been changed by the
> action of light thus creating a "latent" image.Then, all we could do is to
> develop the latent but invisible image as fully as possible. See previous
> postings. Alternatively, another possibility would be to treat the film
> BEFORE exposure to increase its sensitivity. But that was not the
question,
> was it? What we are really thinking about is changing the manufacturers
> rating of a film, innit?
> Gordon wrote.......
> >This is the practice of treating film after exposure, but prior to
> development to >increase a film sensitivity.
> See you. John - Photographist


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