From: Richard Knoppow (dickburk@ix.netcom.com)
Date: 07/17/02-09:32:59 PM Z
At 09:41 PM 07/17/2002 -0700, you wrote:
>Richard wrote:
>
>> T-Max RS developer will also produce higher Dmax than D-76 and is
>> probably easier to find than either DK-50 or D-19. Its also a low fog
>> developer, useful for push processing. It also tends to produce straighter
>> characteristic curves than D-76. I should have mentioned it before.
>
>I have been thinking of switching to T Max actually, but when I used it in
>its 35mm form, I had a lot of trouble processing it so that it wasn't grainy
>or overdeveloped. What is the secret to good processing of T Max? I have
>read that it is "sensitive to inaccuracies in development times." I wonder
>what that means. Also, apparently it has an anti-halation layer that's
>harder to remove than that of other films. I fix in the tube rather than in
>a tray, but I suppose I could put a screen in the tube so that the red dye
>would get removed during fixing.
>
>--shannon
>
I am not sure exactly what makes T-Max film more finicky, perhaps just
the thin emulsion.
An examination of the time vs: contrast curves and time-temperature
tables shows that while about a 33% change in development time results in a
one paper grade change in contrast for most film only a 20% change is
needed for T-Max. Since development is temperature dependant its also more
sensitive to the developer temperature.
T-Max is also capable of very high densities. It doesn't seem to shoulder
off so its possible to get negatives which are hard to print.
Its not the anti-halation dye which is persistent. Rather its a
sensitizing dye. According to Kodak this dye binds to any unremoved silver
complex in the film. This maybe so although extended fixing with rapid
fixer doesn't seem to garuntee its removal. However, a normal treatment in
a sulfite washing aid removes it completely. Since a sulfite wash aid does
remove some otherwise insoluble silver complexes (at least according to the
Kodak labs technical paper describing it) it could well be removing the dye
along with the complexes. In any case, the use of the wash aid results in
perfectly clear negatives. Note that 35mm film has an anti-halation dye
built into the support. Its not removed by processing. Most 35mm B&W
negative film has this pigment and is gray colored.
I use a lot of T-Max for conventional photography and have no problem
getting good negatives with it. The tabular grain allows a very thin
emulsion coating which reduces light scattering resulting in greater
resolution and sharpness. Thin emulsion films seem in general to be fussy
about processing although there may be something else about tab grain films
adding to the fussiness.
Ilford Delta and the new Fuji Acros are tab grain films.
BTW, Fuji film might be another alternative to HP-5. Acros comes only in
ISO - 100 but Fuji makes conventional films for ISO-400 and faster.
While we are expanding choices don't forget Agfa APX-400. I have no idea
how well it works for high contrast use but its very good for conventional
printing.
---- Richard Knoppow Los Angeles, CA, USA dickburk@ix.netcom.com
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