David Rasberry
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Šabović Adis;1863774 said:It sure works with 100 ASA film, no one ever said it wouldn't, but
what if you use film you don't know the ASA of? How do you determine if it's a 50, 100, 250, 500 ASA or in between, whatever? What do you do?
Phil, feel free to chime in! :biggrin:
Simple. Light an 18% gray card or grayscale chart to a meter referenced ISO rating. Bracket chart exposures around that rating and measure the negative or resulting print with a densitometer. I used to do this with each fresh batch of film when shooting works of art for a museum for publications. Different film batches might vary as much as 1/3rd stop either way from the nominal rating on the box.