"Thor Lancelot Simon" wrote in message
...
I happen to have all three sets of Kodak rotary-processing
recommendations
for Tmax 400 in front of me: the old (prior to move to new
coating facility)
Publication F-32, the "new" (first generation at new
coating faciity) F-4016,
and the "newest" (current production, "finer grain!")
F-4032.
Kodak claims that the "finer grain" TMY -- the newest
stuff -- has "slightly"
different processing times than the generation immediately
prior. If their
table is to be believed -- nonsense.
The data in the newest -- F-4032 -- publication, for the
"finer grain"
film appear, for rotary processing of sheet film, to
exactly match the
data in the oldest -- F-32 -- publication, for the "old
coating facility"
film.
Time to plug in the densitometer again and hope it's still
working, I
suppose. I wonder what exactly Kodak is up to: did they
revert production
to how (and where?) it used to be before the first set of
changes?
--
Thor Lancelot Simon
The data sheet you want is F-4043 for the "new"
400T-Max, I have no idea what 4032 is. The latest T-Max data
sheet covering all of the films is F-4016 dated October
2007, however F-4043 is later and covers only the ISO-400
film.
My memory is that a new data sheet was issued when
production of B&W film was moved to the same plant that
coats color film. At that time it was stated that while new
datasheets were issued T-Max films had always been coated in
this plant and there were not major changes. The "new" film
is evidently actually coated on a different machine and had
some adjustments made to the emulsion and to the
overcoating. The overcoating affects development times
because it affects the penetration of the developer into the
emulsion. It has the greatest effect on "induction time"
that is, the time it takes for the image to begin appearing,
but this also shifts all times somewhat and is not
consistent with temperature.
I don't know why Kodak made these changes but suspect
that the production quality had begun to drift too much.
When the films were moved to the color plant it was reported
that Tri-X films, which really were moved to new machines,
had finer grain than before and some found the grain finer
than 400T-Max. This last should have been the case and may
be an indicator that the T-Max line had drifted. It is also
possible that changes in the formulation of the emulsion
were made. I find the suggestion in the new datasheet that
edge sharpness is improved to be interesting because it
suggests such a change.
I don't think Kodak ever just re-writes datasheets for
no reason. However, since the development charts are based
on sensitometric measurements and since these measurements
are made on a continuing basis for tracking the production
quality, its quite possible that at some point there is
enough change to warrant new overall measurements and an
amended datasheet.
--
---
Richard Knoppow
Los Angeles, CA, USA