To test film for normal development you have to produce a bare minimum of two exposures:

ISO speed test

Photo 1B
John M. Grzywacz-Gray

We are doing the simplest possible test.

We are looking for:
zone 1 that has a density of between .09 to .15

zone 8 that has a density between 1.20 and 1.30 for a condenser enlarger

zone 8 that has a density of 1.3 to 1.35 for a diffusion enlarger.

We could also look for Zone 3 values that are around .35

Zone 5 values should be around .65

Zone 8 values determine development

Zone 1 values determine exposure.

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