RE: does flash effect deer - NO
another factor is where the camera is setup. Like GrumpyTom has noticed on a trail when the whiteflash begins to go off deer avoid the area. When I set my cameras up over a corn pile I get pictures of the same deer as long as there is corn. I believe there is no way the deer are happy about a bright flash blinding them in the middle of the night but they tolerate it for an easy meal.