terryroth (terryroth@earthlink.net)
Tue, 23 Mar 1999 16:06:05 -0800
Bob_Maxey@mtn.3com.com wrote:
>
> Factors affecting degree of development:
>
> The density obtained in a developed image depends on the nature of the
> emulsion, the exposure it has received, the degree of development,
> temperature and compatibility of the film and developer. With any emulsion,
> the degree of development depends upon the time of development, temperature
> of the developer, strength of, and freshness, exhaustion, the degree of
> agitation of either the material or solution, how active the developer is,
> etc.
>
> If film does not receive any agitation, developer action slows. This
> happens because the developer in contact with the emulsion, becomes
> exhausted. This does not happen when agitation is done. It is important to
> do this properly because of the likelihood of streaks and mottle.. If there
> is no agitation, exhausted developer loaded with bromide can flow across
> the emulsion from dense highlight areas and produce uneven streaks.
>
> My 2 cents worth,
>
> RM
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FWIW, I have been developing my 5x7 and 8x10 negatives (from camera,
not copy negs) in PMK Pyro, with brush development. I gleaned this idea
from an article a few years back in VIEW CAMERA, I can cite the issue if
anyone is interested. Prior to this, I used the otherwise estimable HP
COMBI tank for 5x7, tray for 8x10 and weas plagued with uneven tonality
in cloudless sky, and some mottling problems in large areas of even
density. The downside: one can only develop 1 8x10 at a time, but the
results are worth the effort--perfectly even tones, even to the
densitometer. You can build the pictured holder, or jut use the
same-size tray and brush away, decreasing development time about 10%, as
there is constant (and effective) agitation. Considerable oxidation,
but overall stain not objectionable with Delta films. FP4+ OK, but HP5+
has more overall stain than with other methods of agitation; just print
down 1/2 stop or so.
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