Archived posting to the Leica Users Group, 2001/12/30

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Subject: [Leica] Re: On agitation
From: Herbert & Lee Kanner <kanner@acm.org>
Date: Sun, 30 Dec 2001 13:40:32 -0800

My belief is that with current films and developers, there is no 
significant difference between sufficient agitation and extra 
agitation.  Correct agitation was of importance perhaps thirty years 
ago, when films were grainier and the fine grain film/developer 
combinations were of low contrast.  There was a flurry of the use of 
so-called "acutance" developers that would produce Mackie lines.  On 
the negative, between a heavily exposed and moderately exposed area 
would be a fine light line.  On the print, this would become a dark 
line and, if subtle enough, would not be noticed but would give the 
illusion of greater resolution.  The light line was produced by local 
exhaustion of the developing agent.  The effect was critically 
dependent on just the right amount of agitation.  Too much, and the 
effect would disappear.

Neofin Blue was the developer I played with around 1970 something.  I 
also made up a home brew "Beutler" developer--I think it was just 
metol and sodium carbonate.  With the home brew stuff, the Mackie 
lines were so strong the the results were interesting but not very 
appealing.  I read that the commercial developers, such  as Neofin 
Blue had proprietary trace ingredients that toned down the effect.

Years later, I bought some Neofin Blue out out of curiousity.  The 
instructions for agitation were entirely different--possibly the 
formula was also different.  It was apparent that it was no longer 
being promoted as an acutance developer.

Herb
- -- 
Herbert Kanner
kanner@acm.org
650-326-8204
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