bngoofy wrote:EV (Exposure Value) to LUX
Any idea how to do this?
The definition of EV=0 is an exposure of 1 second at f/1 using ISO 100 film, or any equivalent thereof (2 seconds f/1.4, 4 seconds f/2.0 etc)
The technical definition of Ev is 2Ev = LS/C.
Where:
â€¢ Ev = the exposure value
â€¢ L = field luminance
â€¢ C = Exposure Constant - If you use candelas/ft2, it is 1.3. If you are using LUX (candelas/m2), it is 12.5.
â€¢ S = film speed following the ISO standard
Now, as far as where I think you're trying to go with this... Consider that 2ev = A2/T
where:
â€¢ A = the f-stop number of the aperture
â€¢ T = shutter time in seconds
Combining these two; EV = log2(A2/T) = log2(LS/C) - This is perhaps the most vital formula there is for understandiing the basics of the mathematics behind photography.
I hope this helps!
William J. Knight
Health Physicist
Los Alamos National Labs