Anything above 10x50 will present difficulty keeping steady enough to view properly and be heavy to hold up for long periods of study. I use 10x50 bins for stargazing and without a tripod I can't see the Galilean moons but with a tripod I can. Also be aware that the exit pupil size matters, and for astronomy you want a larger exit pupil. 10x50 give a pupil size of 5mm which is a good size for night work.