Re: Pyro Developers

From: Sandy King ^lt;[email protected]>
Date: 04/04/04-10:48:56 AM Z
Message-id: <a06020446bc95e4fc68b6@[]>


As Carl Weese notes, the way that developers render tonal values is
at least as important as definition. There are indeed some high
accutance developers that give greater resolution than the pyro
developers I mentioned but they do so at the loss of some smoothness
of tone.

I am aware of the difference between resolution/accutance and
sharpness and of the importance of contrast. You should therefore
assume that for the comparisons I mentioned 1) time of development
was such that both tests were developed to the same CI, and 2)
physical development was identical so that any differences observed
in adjacency effects must result from the formula itself and not from
the method of agitation.

As for the resolution limits please correct me if I am wrong but my
thinking is this. If I expose two negatives on the same roll of film
with the same camera and same aperture setting any difference in
resolution observed must of necessity result from either the
developer or method of development. That is to say, the limit to
resolution in this case can not be in either the film or in the
optical system.
So what I am observing is that the film I used (TYMAX 100) and the
optical system appear appear to be capable of resolving well over 100
lpm (in the center of the file) so that the developer itself, and not
the film or optical system, establishes the limit for resolution.

Sandy King

>Subject: Pyro Developers
>Date: Sun, 04 Apr 2004 00:05:01 -0500
>> So, how to resolve the question of whether certain pyro developers
>> give sharper results than traditional MQ developers?
>Based on your motivation, shouldn't you compare non-tanning accutance
>developers against tanning accutance developers? Those developers you
>tested do not give particularly good accutance when compared to those
>optimized for sharpness.
>> See the point? With any film the Pyrocat-HD negative will resolve
>> about 10-15 lpm more than the D76 negative. Same would be true of
>> other commonly used MQ developers such as HC-110, DK-50, etc.
>Minor point: AFAIK, HC-110 is not an MQ developer.
>What are the contrast and resolution limit you are dealing with?
>What are the films where the differences are minimum/maximum?
>Resolution and accutance/sharpness/definition are different things,
>but resolution depends on the contrast and accutance is a consequence
>of manipulated local contrast. So, in somewhat low contrast with
>fairly step-like pattern (stepwise change from low irradiation to high
>irradiation in iexposure), difference of that degree is not
>surprising. More relevant to practice is when the irradiation level
>transition is somewhat gradual. Somewhat idealized testing is
>modulation transfer function of sinusoidal grading targets of various
>spatial frequency, at various fixed target contrasts. Significant
>adjacency effect would increase the modulation transfer, and MTF often
>show broad peak in middle frequency range because of this. This is
>more relevant and direct indication of the adjacency/accutant effect,
>but it would require a serious setup to run a test...
>Ryuji Suzuki
>"All the truth in the world adds up to one big lie." (Bob Dylan 2000)
Received on Sun Apr 4 10:53:04 2004

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