[Bill Burk]

Attachment 63191

Michael R 1974,

Yes Stephen made a tiny typo, he meant Flare factor.

But look at this chart again. Now imagine doing a single-tone film speed test where you meter Zone V and stop down 4 stops (or 4 1/3 stop if you prefer).

When you stop down, you move everything down.

In the middle of the graph, Zone V, the meter point... you see the exposure+flare (realistic exposure) curve practically rejoins the theoretical exposure (45-degree theoretically perfect) curve. So a test exposure is not influenced much by flare.