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 ?

  • 1
    Probably best asking this on physics.stackexchange
    – MikeW
    May 26 '13 at 0:00
  • Maybe How to calculate Lux from EV?
    – mattdm
    May 26 '13 at 4:43
  • I think the linked question contains the information you're looking for.
    – Joanne C
    May 27 '13 at 0:44

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

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