Manuel Viet wrote:
> Depends on the film, but I know from a reputable source that the TMZ (tmax
> 3200p) is a true 800 iso, and 3200 is a pushed-process, marketing hype only,
> selling figure.
>From Kodak Tech Pub F-4016, quoted without any sort of permission:
--quote--
KODAK PROFESSIONAL T-MAX P3200 Film is specially designed to be used as
a multi-speed film. The speed you use depends on your application; make
tests to determine the appropriate speed.
The nominal speed is EI 1000 when the film is processed in KODAK
PROFESSIONAL T-MAX Developer or KODAK PROFESSIONAL T-MAX RS Developer
and Replenisher, or EI 800 when it is processed in other Kodak
black-and-white developers. It was determined in a manner published in
ISO standards. For ease in calculating exposure and for consistency with
the commonly used scale of film-speed numbers, the nominal speed has
been rounded to EI 800.
Because of its great latitude, you can expose this film at EI 1600 and
yield negatives of high quality. There will be no change in the grain of
the final print, but there may be a slight loss of shadow detail. When
you need a higher speed, you can expose this film at EI 3200 or 6400. At
these speeds, there will be a slight increase in contrast and graininess
with additional loss of shadow detail. (See the processing tables for
adjusted development times.)
Because of the shape of the characteristic curve of the film, you will
obtain better shadow detail and highlight separation when you expose it
at EI 3200 or 6400 than you can obtain with 400-speed films pushed by
3 stops. These higher speeds allow you to take photographs in many
situations where photography was previously impossible.
To expose this film at speeds higher than EI 6400, it is critical that
you make tests to determine if the results are appropriate for your
needs. For best results when you expose the film at these speeds, use
XTOL, T-MAX Developer or T-MAX RS Developer and Replenisher.
--end quote--
Apparently you are quite right, it is nominally ISO 800, but designed
for better underexposure characteristics than other films.
Jonas
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