Just as the title says, how do I accurately calibrate\determine the accuracy of a light meter.
I have a Weston Master II and I know I can set the zero point from the back, but how will I know that the number of foot candles it reports is accurate?
I can compare it to other cameras, but when I do that on the Rebel 2000 I get the same result and a different on the AE-1. So, I don't think that is a good answer.
Answer
Most calibration is done by comparing a device under test to one that's known good or by using a calibrated reference source. Many metrology labs offer this as a service, usually in ways that can be traced back to NIST or another standards organization. The cost will be many times the value of your Weston meter.
The zero point adjustment on your meter puts a mechanical offset on the needle, which makes it easy to calibrate for no light. If there's anything in the meter's electronics that's causing error, there's not going to be much you can do to adjust it other than cleaning the potentiometer surfaces.
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