If you want to maximize what you can see in hand-holdable binoculars, the image brightness and vibrant color you get from the United Optics MS 10x50s should put them on your short list.
Pros: Very good optical and mechanical quality.
Cons: Some edge-of-field aberrations.
The first time you take the binoculars out of their rugged military-style padded nylon case, you sense that you are holding something a bit different. The somewhat retro-looking synthetic leatherette armor that covers the substantial 47 ounce (1320 gram) magnesium alloy body conveys an impression of old-school functionality. The silky smooth operation of the hinge and individually focusing eyepieces, all of which have sufficient resistance to preclude accidental adjustment, just ooze class.
If you are used to lesser-quality 10x50s, when you take these under a dark sky you’ll immediately notice how much brighter they are. Stars are very sharp over the central 80 percent of the 6.5 degree field of view, and I could see dark space between the two components of Delta Cephei (40 arcsecond separation) out to just less than 90 percent. The outer 5 percent is noticeably vignetted.
Control of false color (chromatic aberration) is very good on-axis, but becomes noticeable on bright objects (e.g. Venus or the lunar limb) once they are off-axis, although it is still well-controlled and not overly obtrusive here. I did not notice it at all on first magnitude stars, although the color of Mu Cephei seemed to change slightly towards the edge. Color correction is quite sensitive to eye positioning: you do need to ensure your eyes are on-axis to get the best color fidelity.
Consequently, color rendition is good. The varied colors of the stars in Orion’s Meissa cluster is immediately apparent. Also in Orion, the Great Nebula (M42) itself looked delightfully crisp and bright; the more I looked, the more structure became apparent.
Stray light is very well controlled although, if you try hard, you can get Venus or a bright Moon to produce a slight reflection off the edge of a prism. Unsurprisingly, contrast is excellent; under suburban skies these binoculars are delightful to use, but under truly dark skies they are stunning.
The waterproofing (IPX7 specified) and dry nitrogen filling mean that you won’t need to be concerned about corrosion due to moisture ingress on dewy nights. The case is sturdy enough to offer good protection, the lens caps fit and do not fall off, and the neoprene neck-strap is comfortable enough over a jacket collar.
I have the Lunt Solar Systems Magnesium version of the binoculars, and use them regularly. The only noticeably better 10x50s I have used are premium binoculars costing more than $1000 USD more. These are keepers.
Summary: Ideal for someone who wants a very good astronomical 10×50 for hand-held use.
Original Review: http://binocularsky.com/binoc_reviews.php
Ed. note: This model has been replaced by a new one so you may not find it available from retailers.
