Best binoculars for stargazing (astronomy binoculars)

How these binoculars were chosen

A model makes this list when its objective lens is 50 mm or larger and its exit pupil works out to 5 mm or more. Each series appears once, in one size, most popular first. Field of view, eye relief, close focus and weight come from the makers' documents.

The exit pupil is calculated from the size, since Nikon defines it as the objective diameter divided by magnification. Where a maker prints no figure, none is shown.

Picks for every use and price are in the main best binoculars list.

What the 50 mm and 5 mm rule means at night

Nikon says a larger exit pupil gives a brighter view in dim light, and that the human pupil opens about 2 mm in daylight and 7 mm in the dark. A 7x50 gives a 7.1 mm exit pupil, which fills a dark-adapted eye. A 10x50 gives 5 mm.

Age changes the picture. Practical Sailor, citing NIH data, reports a mean pupil of 7.33 mm for ages 20 to 29 and 5.58 mm for ages 60 to 69. For older eyes, a 5 mm exit pupil already uses most of the opening.

The Astronomical League recommends objectives of 50 to 80 mm for its deep-sky binocular program, and its author observed with 7x50 binoculars. The Royal Astronomical Society names 8x40 or 10x50 as the usual sizes to start with. The British Astronomical Association names 10x50 and 7x50 as good sizes.

Holding steady under the sky

The British Astronomical Association says anything above 10x is difficult to hold and should be mounted. Audubon explains why: a binocular that magnifies eight times also magnifies hand movement eight times. The SkyMaster 12x60, at 39.2 oz, is the one model here above 10x, so a mount suits it.

Celestron says a tripod is not required at 8x to 12x but becomes necessary at 15x and higher. Eight of the models here are tripod adaptable by their makers' figures. Vortex states its adapter fits tripods with a 1/4"-20 socket, and the binocular tripod adapters page covers the fit.

Weight matters when you look straight up for minutes at a time. The median weight across the 10 models is 32.7 oz. The Prostaff P7 weighs 22.2 oz and the Monarch weighs 22.6 oz, while the Commander reaches 38 oz.

Choosing between the 7x50 and 10x50 models

The 7x50 models, the Cometron, Commander and Marine, trade magnification for a 7.1 mm exit pupil and a wide field. Their fields run from 267 ft to 420 ft, against a median of 321 ft for the whole list. A wide view makes star fields and large clusters easier to find.

The 10x50 binoculars bring more magnification and a 5 mm exit pupil. Field of view across the five 10x50 picks runs from 314 ft to 346 ft. If you wear glasses, 8 of the 9 models with a printed eye relief offer 16 mm or more, a figure the RSPB treats as the mark for eyeglass wearers.

Close focus matters little at the stars, but it helps when you also watch nearby subjects. The Diamondback focuses at 6 ft and the median across the list is 20.5 ft. The Steiner models focus no closer than 66 ft.

What this list leaves out

Models with objectives under 50 mm, such as 8x42, are left off, even though the British Astronomical Association calls 8x40 a good lighter size. See best binoculars compared for the full range, or stabilized binoculars for image stabilization.

Larger astronomy glasses at 15x56 and above, or 25x100, are mount-only instruments and sit outside a list built for hand holding. Use the exit pupil calculator to test any size you are considering.

The short answer

For the widest field and a 7.1 mm exit pupil, the 7x50 models lead, with the Commander at 420 ft. For more power in a 5 mm exit pupil, the Prostaff P7 at 22.2 oz is the lightest 10x50. The SkyMaster 12x60 gathers the most light and wants a mount.