I remember, oh so many years, ago, when the standard astronomy binocular was a
7x50. This was before the advent of giant binoculars, back when the
astronomy binocular was seen as little more than an add on or supplement to a
telescope, but never a subsitutue for a telescope. Binocular astronomy had yet to achieve a status as a type of astronomy all its own. The binocular universe was overall quite different, too. The most common binocular was a 7x35 - the 8x had yet to achieve its present popularity. It was only natural, I suppose, to go with a 7x50 for astronomy, then, especially because there were so many 7x50 binoculars available, either in the form of a
military 7x50 binocular or a
marine 7x50 binocular. Even though the astronomy binocular landscape has changed, considerably, a good 7x50 still reamins a worthy tool for astronomy, especially if you want those big, wide field views of open star clusters and nebulae.