Moment of enlightenment, in camera (8)
I believe the answer is:
exposure
But I can't explain it at all! Could you help me understand?
(Other definitions for exposure that I've seen before include "O pure sex! (anag.)" , "The harmful effects on the body of extreme cold" , "being unmasked" , "Laying open to public view" , "Disclosure - made by a photographer?" .)