Originally Posted by
Michael R
You have to start with some parameters held constant. All other things being equal (film size, exposure, emulsion, developer, agitation frequency, magnification), as total contrast is increased/decreased, local and micro contrast will follow. However changing those variables can have effects on the relationship between large-scale and "micro" contrast. A hypothetical example for a given film (without getting into specific developer details):
Starting point: Development to normal contrast index in a general purpose solvent developer, with normal agitation
Scenarios for lower target contrast index relative to starting scenario:
1) Same as above, with shortened development time: In comparison to the starting point scenario, total contrast, local contrast and micro contrast will all be lower
2) Change to low-sulfite/dilute developer with minimal agitation: In comparison to the starting point scenario total and local contrast will be lower, but micro contrast might be maintained or possibly increased
These are gross generalizations meant as an illustrative example. Also note the discussion has been limited to contrast effects.
@Drew: There are many different types of masks as you know. I'm referring here only to "classic" unsharp masks, which are normally designed to reduce contrast at all scales higher than "micro", allowing the negative to be printed at higher contrast, thus boosting micro/edge contrast relative to total and local contrast. This can enhance the overall subjective sense of crispness and delineation of detail.
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