Telescope Reviews: Need help choosing binoculars

Angel
I just cut these passages from another post and pasted so I wouldn't have to type it all over. It's long winded, but it answers some of your question.

All binoculars were mounted on stable tripods. Viewing from my front yard. Light pollution not evident, but city lights 15 miles away on the southern horizon.

Summary Results, in NELM 5.6-5.8 skies:
Oberwerk 20x80 see mag10.8 direct (lower NELM skies).
Fujinon 16x70 see 10.8 direct.
Oberwerk 15x70/03 see 10.7 direct, 10.8 averted.
Oberwerk 15x70/02 see 10.5 direct, 10.6 averted.
Pentax 16x60 see 10.5 direct, 10.7 averted, some brighter not seen.
Pentax 12x50 see 10.3 direct, 10.5 averted, some brighter not seen.
Orion 10x50 see 10.0 direct, none fainter averted.
Swift 8x42 see 9.5 direct, 9.8 averted.

It was very difficult even with the best 70mm binoculars to see stars beyond mag 9.7. A passing glance in the eyepiece would not show stars beyond 10th mag. It required a concentrated period at the eyepiece, allowing gaze to move around. Once glimpsed, stars beyond mag10 could then be seen directly.

More than once I noted that bumping the binoculars and causing any minor shake eliminated most stars over mag 9.0 from view. As soon as they settled quite after 5 or 10 seconds, 9.5 and 9.7 mag stars were readily seen. Absolute steadiness and some persistence is required to see mag 10.2 and 10.3. Continued persistence and effort is required to see mag 10.4. Stars beyond that are not seen in any binocular without expending a considerable concentrated effort, sometimes over as much as several minutes.

Without a steady mount the average observer is probably not seeing beyond mag 9.5 with any binocular up to 70mm. Hand held observations with most of the above binoculars gave results 0.5 to 1.0 mag less than when mounted. Without considerable effort the average observer is not seeing much beyond mag 10.2 to 10.3. The practiced observer using 70mm mounted binoculars will see stars of 10.5 to 10.8 only with considerable effort and absolutely still binoculars.

It is not likely anyone will see mag12 stars in anything but the largest (100mm or larger) binoculars under mag 6.5+ skies.

All of the above pertains only to limiting magnitude. there would be considerable differences for all of these models if used for faint extended objects such as nebula and galaxies. This is where there would be a very wide difference in the 8x56 vs 15x70. In most skies that 8x56, with it's 7mm exit pupil, is going to provide a washed out view.

8x56 would be most beneficial to you if you could get them under very, very dark skies, assuming your eye pupil opens wide enough to accept all the light they would deliver. Otherwise, in normal <mag6 skies choose something with a smaller exit pupil.

Even on faint extended objects, magnification shows so much more detail that I would recommend getting the highest magnification that allows you to still hand hold. You will see a lot more when you mount them.

Binoculars are generally designed to deliver maximum brightness, but you must be able to use it all. If you have opportunity to sometimes or often get to real dark sites, a 7mm exit pupil will provided maximum brightness, but only if you can use it all. Most often, it will do so at a considerable expense of lower magnification. have someone measure your pupils for you. If yours are 4 or 5mm, you won't need 7mm exit pupils in binoculars. In that case go for a slightly higher magnification and let binocular exit pupil drop to 5mm.

Hand holding is fine for a quick look. You will see dramatic improvement with mounting. That was pointed out above. You are looking for something that you can use either way. 12x or 10x will work effectively for both. 8x is a little low for astronomy. 15x is a little high to be hand holding.

edz

--------------------
Teach a kid something today. The feeling you'll get is one of life's greatest rewards.
member#21