Medium-aperture astronomical binoculars that deliver vibrant high contrast images.
Pros: Very good optical and mechanical quality.
Cons: Some edge-of field aberrations.
70mm astronomical binoculars occupy a versatile niche: although they work best when they are mounted, they can also be handheld for short periods.
The United Optics MS 16×70 binoculars (MSRP: $615) , which are well-protected by a rugged padded nylon case, will be covered either by leatherette or ribbed rubber, depending on the brand. (You can find the binoculars branded as Lunt Solar Systems Magnesium, APM, Omegon Argus or Helios LightQuest.)
This armor covers a lightweight magnesium alloy body, in which the prism housings are integral to the objective tubes. There is no “stiction” in the smoothly operating individually focused eyepieces, which have pliant rubber fold-down eyecups and knurled rings that makes focusing easy even if you are wearing thick gloves.
The objective tubes appear to be unusually long; this is because the focal ratio of the lenses is higher than the f/4 that is typical for binoculars. The optical phenomenon in less-pronounced optical aberrations, and the resulting optical quality is immediately apparent under a starry sky. The 8-element eyepieces snap to a very sharp focus, and the color rendition is excellent. Even in this non-extra-low dispersion glass (ED) version, control of false color (chromatic aberration) is very good on-axis, and is not overly obtrusive off-axis on bright targets such as Venus or the lunar terminator. The chromatic aberration is quite sensitive to eye positioning, however, so you will need to ensure that your eyes are on-axis if you are going to get the full benefit of the view.
The 4.1-degree field of view is flat except at the periphery, where it is affected by slight field curvature. The double star Albireo (separation: 34 arcsec) was cleanly split over the central 90 percent of the field of view. There is also a small amount of positive (“pincushion”) distortion, which is necessary to eliminate the nauseating “rolling ball” effect that can occur without it.
The binoculars excel when you turn them to the larger, deep sky objects. The Andromeda Galaxy (M31), for example, shows good gradation of intensity from the spiral arms to the core, and you can easily see the sharper cut-off in brightness caused by the dust-lane on the nearer edge. Even relatively tiny objects such as the Dumbbell Nebula (M27) show a distinct shape and a hint of structure. The resolution is due to the excellent image contrast, which is itself due to premium anti-reflective coatings on the optics and very effective stray light control.
You’ll want to mount these binoculars to get the best out of them. A monopod and trigger-grip head is ideal, and helps preserve the portability of your binocular observing kit. If you hold the mounted binoculars by the ends of the long objective tubes, they can be rock-steady on the monopod, even when it is angled to the vertical and you are observing seated or reclined.
The waterproofing (specified as IPX7) and dry nitrogen filling mean that you’ll not need to be concerned about water-related corrosion on dewy nights, adding to their utility.
These are lovely binoculars that have become a favorite of those who have used them.
Original Review: http://binocularsky.com/binoc_reviews.php