Hi Dave,
Seriously though, few on this forum would question the value of magnification for seeing fine details at distance--in those situations a 10x has advantages over 7x. But once you get to know birds, very few IDs need be made on the basis of fine feather details, or on those alone. And in many types of terrestrial birding (shrubby areas, grassland, woodland), the vast majority of birds that are seen are spotted at distances at which most fine details are visible, in which case the much larger FOV and DOF of 7x binos may be a much bigger advantage than modestly higher magnification. I much prefer 7-8x binos over 10x, even in open country, mudflat, and seashore/lake situations. In these situations the extra 20-30% magnification of a 10x just isn't enough to satisfy for distant viewing, so out comes the scope. I wonder if some of the strong differences in opinion over the need for 10x relate to differences in visual acuity? My own vision is around 20/12, so by my rough reckoning, I guess I see about as much detail in a 7x as someone with 20/20 vision (the usual standard of "perfect" vision) sees in a 10x. If I had poorer vision, maybe I'd be more inclined toward 10x.
