Originally Posted by
ic-racer
Contact it to the paper tightly so no light leaks around. If light leaks around the dense strips this will mess up readings. If you just want to measure contrast, expose so the entire scale fits in the step tab. If you want to compare paper speeds, you need to do some trial to get the correct exposure time so your speed point shows up in all the tests without altering the time.
Cheap and dirty way to determine the conrast. Count the strips between the darkest and lightest. Multiply by 15 to get ISO(R).
So if 5 gray strips are present, 5 x 15 = ISO(R) = 75 = about 3.5 grade.
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