Originally Posted by
guyatou
Hello all --
I have a quick and fairly basic question. I've searched high and low, and can't come up with a definitive answer.
My light meter has settings for ISOs down to ISO 3. I've been shooting Rockland dry plate tintypes, which are about ISO 1. How many full stops are in between? Basically, how many stops do I need to add in order to meter at ISO 3, but get the correct amount of light for ISO 1?
Does the scale (in full stops) go:
ISO 1
ISO 3
ISO 6
ISO 12
ISO 25
ISO 50
ISO 100 etc.
Or am I missing a stop, like ISO 1.5?
The tintypes I shot were all a bit underexposed, but I was also having to add for bellows factor, etc., so my calculations could have been off anywhere along the line.
Does anybody know the answer off the top of their head?
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