for me typically 30 seconds to a minute w/o a break-particularly if the bin is heavy! how long is it usually necessary to hold up your bins while looking at a bird? what if you've IDed it but you want to keep looking for giss? how long do you typically hold up your bins until your arms hurt?
I think that would depend on how heavy your binocular was. [
]
Seriously though I think it would depend on a variety of factors including the weight of the instrument, the type of birding activity, if there was any support involved and how cooperative the bird is, etc.... I have never attempted to measure the length of time that I hold the binoculars up to my eyes and believe it would vary because of the reasons mentioned above.
Don't laugh. I am not crazy. I have 2 weights, 4 pound each, that i lift from belt to my forehead, 100 times per day. I've noticed serious improvements in my ability to hold steady for long times a pair of Ultravid 10x42 while looking straight up.