Re: Pyro Developers

From: Ryuji Suzuki ^lt;[email protected]>
Date: 04/04/04-04:20:45 AM Z
Message-id: <>

From: 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 04:25:42 2004

This archive was generated by hypermail 2.1.8 : 05/14/04-02:14:31 PM Z CST