Aside from stiff turn rings, focusing adjustments and so forth, all of which I avoid at all costs and simply look long enough to see/shoot. Besides the obvious problem of breathing in the presence to cold glass and fogging it, the near position of a warm moist orb (eyeball) can fog the lenses of binoculars.
And when it comes to scopes, make sure any sighting you do, if you have to make any setting changes to the crosshairs, is reverified after warming the scope up completely and bringing it back out and allowing it to cool down again. Some scopes will gives you fits because they won't move properly when they're very cold; warm them up and whatever adjustments you've made will happen, then you need to reshoot the rifle to verify (since you may not have made substantial progress when the unit was cold).
