[pure-silver] Re: TMAX grain - developer modification?
- From: Ryuji Suzuki <rs@xxxxxxxxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Tue, 12 Oct 2004 07:37:26 -0400 (EDT)
From: "John Black" <jblack@xxxxxxxxx>
Subject: [pure-silver] Re: TMAX grain - developer modification?
Date: Mon, 11 Oct 2004 11:37:39 -0400
> There is no doubt that precieved grain and pH of developer are
> linked. The higher the pH, the greater the activity and precieved
> grain.
I agree, but this and "clumping" are different things. Depending on
the developing agent/solution, the way grain gets developed varies
and some appear coarser than others.
Also, even in heavily exposed areas, not all grains are
developed. Simply comparing developed grains without knowing the
unexposed crystal size/shape distribution can be misleading, because
you may find one type of crystals developable in one developer but not
in another. For example, some developers don't exploit crystals that
have internal latent image centers, while others do. Coalescence
crystals are more likely to have crystalline lattice defects etc. than
normal crystals and these most likely influence the way latent images
are formed, and thus how differently they are developed in different
developers.
Silver halide crystals are densely packed in coated layers. When
people study these things using EM, they usually have to prepare very
dilute emulsion to put on the specimen grids. Otherwise, the picture
is too crowded no matter how thin they coat the emulsion.
--
Ryuji Suzuki
"Keep a good head and always carry a light camera."
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