HI all, I've got a gossen luna pro F, and I'd like to use it to measure lumens or footcandles in my greenhouse to see if a particular orchid I'm growing is "getting enough." I remember running across a formula that used a particular ISO setting to directly correlate the f stop reading on the incident light reading to foot-candles... but I can't find it anywhere. Any suggestions from our engineer pentaxers out there?
Thanks Sid B
