I meter a surface at ASA 100 and get F4 at 1/15 second. What is the illumination coming off that surface in Cd/square foot ?
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1Probably best asking this on physics.stackexchange – MikeW May 26 '13 at 00:00
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Maybe How to calculate Lux from EV? – mattdm May 26 '13 at 04:43
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I think the linked question contains the information you're looking for. – Joanne C May 27 '13 at 00:44
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This Kodak reference for estimating luminance and illuminance may help.
Your metering at ISO 100, 1/15th and f/4 would be equivalent to ISO 400, 1/30th and f/5.6 if I've done the math correctly. So use their value for f/5.6 which is 2.67 Cd/ft2
MikeW
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