There is a thing at the temple called "the crypt passage" "o-kaidan meguri" where you crouch and walk through a pitch black tunnel until you touch a large key on the wall. You are forbidden from allowing any light in the tunnel and they stressed this to me multiple times. no camera, mobile phone, wristwatch, camcorder.
Toward the end of the tunnel some jerk turned on his mobile phone and lit up the entire thing to walk out. But it was a Japanese zoomer breaking the rules, not a stupid American.