Dave i absolutely beg to differ on that one, i can catagoricaly state that i have on several occasions noted deer bieng spooked by the reflection and flash from a scope lense of from binoculars. It took me a couple of years to work out why the hell a deer on an open hill, with nothing around it, between 300 and 1000m away would suddenly bolt for cover. time and time and time again i've seen the same thing, finaly working it out that the flash was spooking them,i figured it out after me and a mate where glassing each other to read hand signals, we where about 800m apart, the flash from his big 56mm bino's when they caught the sun was far more than i imagined it ever would be. Now i don't expect the deer have worked out its a scope rifle or binos, but the flash just spooks em. I treid out a little experiment with a signaling mirror a couple of times, same effect, deer bolting for cover.
A sun shade on the scope and some scrim scarf draped over optics helps to some extent, as does bieng carefull and aware of catching the worst of the suns glare,, tacticaly a kill flash is an absolute must after sun up and before sun set.