From: Richard Knoppow (dickburk@ix.netcom.com)
Date: 07/19/02-03:34:59 PM Z
At 10:09 PM 07/18/2002 -0700, you wrote:
>Thanks, Richard, for the encyclopedic (as usual) answer to my question about
>developers for T Max. I have one further question:
>
>> There are two T-Max developers (thanks, Kodak). T-Max and T-Max RS. They
>> are slightly different although both appear to be Phenidone-Hydroquinone
>> developers.
>> Both developers tend to produce long straight line characteristics, low
>> fog, and are capable of very high Dmax. They are medium grainy.
>
>I thought that the whole point of tabular grain films was to reduce
>graininess. That's why I was surprised and dismayed when my 35mm T Max
>experiments looked grainier than Tri X developed in D 76. Of course
>graininess is not as bothersome in contact prints as it is in enlargements;
>still, why did they develop tabular grain films if using the developer that
>was designed to go with them makes them look grainy?
>
>--shannon
>
Well, they are less grainy than other films in the same developer.
Both T-Max developers fall into a sort of middle range of developers which
are not either fine grain or extra grainy. DK-50 and other conventional
developers are about the same. I think T-Max was devised to get maximum
speed out of film and to be a very reliable long lived developer, all of
which it does. However, its not a first choice for 35mm.
D-76, which has been around since 1926, has become the bench mark against
which other developers are measured. It was originally intended for
developing very fine grain (for the time) motion picture negative
duplicating film. It rapidly displaced other developers in use at the time
for general motion picture negative work. It offered finer grain, better
film speed and better controlability and predictability than the mostly
Pyro based developers used then.
Two factors contribute to low graininess in a developer: enough sulfite
to provide some halide solvent action, and low pH and high salt content,
both tending to prevent softening of the gelatin. Softening of the emulsion
allows the developing silver crystals to migrate toward each other
producing "clumping". Mostly the grain visible when examining a negative is
due to clumping, the actual silver particals are microscopic. The sulfite
changes the way the silver grains are formed, tending to produce
filimentary shape. Rodinal tends to produce more grain than other
developers due to its very high pH (it uses hydroxide) and low sulfite
content.
Some solvent action, as with D-76 or D-23, raises film speed a little by
exposing development centers beneath the top layer of the crystal. More
solvent action yields finer grain but also lowers the speed again because
it begins to dissolve some of these development centers. Extra-fine-grain
developers like Microdol-X, or the old Kodak DK-20 are in this catagory.
Xtol is a remarkable compromise since it produces grain as fine or finer
than D-76, slightly higher film speed, and no shouldering off. It is also a
good push processing developer.
Now, T-Max has been adopted by Kodak as a trade-mark applied to both film
and developer. However, the two simply share a name. T-Max developer was
not devised to give the best possible results with T-Max film. Most of the
research on T-Max film was done with D-76.
If you process T-Max 100 in Microdol-X, undiluted, the grain is nearly as
fine as Technical Pan although the resolution is not as high. Speed is
around ISO-40.
---- Richard Knoppow Los Angeles, CA, USA dickburk@ix.netcom.com
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