[pure-silver] Re: Development modifications for higher sharpness

From: "Koch, Gerald" <gkoch02@xxxxxxxxxx>
Subject: [pure-silver] Re: Development modifications for higher sharpness
Date: Wed, 27 Apr 2005 13:10:40 -0400

> Perhaps "energetic" would be better than high energy.  But still
> somewhat vague.

What's energy in general?
What's energy in the context of developers?
What changes energy in developers?

> I have seen the following statements concerning the addition of iodide
> to the Beutler formula.
> 
> 1. Addition of iodide can emphasize flare and lens aberations.
> 2. Not needed for modern emulsions.
> 3. Never did anything anyway.  The amount has been described as being
> homeopathic.  (I particularly liked that comment about homeopathy, ie,
> quack medicine.)

Sure, all sorts of things are said about virtually anything in
darkroom literature. The question is what is correct, what is
relevant, and what is practically useful.

Influence of iodide in developer solution depends on the
concentration.  In a very small dose, on old fashioned emulsions, work
as anti-restraining agent. So your number 1 can be in operation in
this case. In light of various techniques used in emulsions to
facilitate development reaction in modern films make the number 2 more
plausible. I disagree with the number 3.

If you want to take advantage of increased adjacency effect by
adjusting the iodide level, I might add that the window of useful
iodide concentration can be fairly narrow and emulsion dependent.
Similar effect can be achieved by careful adjustment of developer pH
in DS-12 type developers. But no matter which technique you choose, if
you make film develop on the edge, the result becomes erratic. I
seriously suggest that kind of risk and frustration is unnecessary in
serious darkroom operation. If you seek exaggerated effects, digital
manipulation is a more effective approach than trying to make a
complicated chemical system work near a critical point.

--
Ryuji Suzuki
"Keep a good head and always carry a light camera."
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