It really depends on the individual deer. Some don't mind a bit and keep coming back. Others will turn inside out and jump out of their skin when a flash goes off. I've seen it myself and it is also featured on one of the newest Drury DVDs where they show a monster buck that freaks out and takes off after one of their cams flash goes off on him. The buck runs out of sight and never stops to even look back. [&:]

Atleast a digital is silent after it takes a pic because more deer actually spook from the actual camera noise and advancing film than they do by the flash.