These binoculars are massive and require the equally massive tripod for support. I moved them once from the living room downstairs to my deck for astronomical viewing ... Never again. These binoculars are unsuitable for astronomical use, except for low moon (great dimensionality) observation, because you can't elevate them enough for comfortable viewing. For astro use, 45 degree eyepieces are required (a different model). They are also unsuitable for birds in flight since they are awkward to aim. I use handheld binoculars routinely for BIF.
I seldom use the 40X eyepieces since the image isn't as bright and has a very narrow field of view. The apparent magnifcation is not much greater than 25X and the clarity seems worse than 25X so that even for distant viewing I prefer 25X.
Focusing is difficult because there is a lot of twisting needed for each eyepiece separately.
Fortunately I have a 100 mile panoramic view and tons of wildlife so that the binoculars get plenty of observational use from their permanent location in my living room.
Before you buy these binoculars be aware of their limited utility. These are not general purpose binoculars. I recommend these only if you have panoramic vistas or live in a military fortification.
Pros: Good optics, very good tripod, impressive glass
Cons: Awkward to focus, aim or transport. 40X not that useful.
This review was written in the old system and had content requirements that are different than reviews written today.