Two eyes, a wide field, and no setup at all
A pair of binoculars is the instrument most often recommended before a first telescope and most often abandoned afterwards, which is a shame, because the wide field and the use of both eyes show sweeps of the Milky Way that no telescope frames. The two numbers in the name are the magnification and the aperture in millimetres, and dividing the second by the first gives the exit pupil — the width of the cone of light leaving the eyepiece. If that cone is wider than the pupil of the observer, the surplus light is thrown away — and since a dark-adapted pupil measures around 7 mm in a young adult but commonly 5 to 6 mm by about fifty, the same binoculars deliver differently to two people standing side by side. That 7 mm figure is exactly why the 7×50 became the classic night glass: 50 divided by 7 is a hair over seven. The true field of view, given in degrees, tells you what actually fits; it is not the apparent field printed in some listings. Prism glass separates the shelf more than most buyers expect: BAK-4 prisms deliver a round exit pupil where BAK-7 prisms cut the edges into a square. Above roughly ten times magnification, a hand-held image trembles enough to hide what the aperture collected, so read the tripod thread as a specification and not an extra. Eye relief decides whether spectacles can stay on. We compare aperture, magnification, exit pupil, true field of view, prism type and coatings, eye relief, close focus, weight, tripod mounting and supplied accessories.
10x magnification · 50 mm objectives · 360 g
A waterproof 10x50 with BAK4 prisms, fully multi-coated optics and 25 mm eyecups, published at 360 g.
Best for: Long hand-held sessions where weight is the deciding factor
≈ €50
12x magnification · 50 mm objectives · 4.2 mm exit pupil
A 12x50 with an 18 mm prism and 50 mm objectives, supplied with a carry case, neck strap and cleaning cloth.
Best for: Daytime distance viewing, with astronomy from a braced or seated position
≈ $69 / £61 / €60
10x magnification · 50 mm objectives · porro prisms
A long-running 10x50 porro binocular from Bushnell’s Falcon line, with coated lenses and no gas filling or weather sealing claimed.
Best for: A first pair kept in the car for whatever the sky or the day offers
≈ $47 / £53 / €52
10x magnification · 50 mm objectives · 5 mm exit pupil
A 10x50 with BAK4 prisms, fully multi-coated objectives and individual dioptre adjustment, sold as an all-rounder for nature, hunting and astronomy.
Best for: A first astronomy binocular where the exit pupil matters more than the badge
≈ €74
10x magnification · 50 mm objectives · 5 mm exit pupil
A 10x50 porro binocular from Nikon’s Action line, described by the maker as suitable for spectacle wearers and easy to hold.
Best for: Sweeping the Milky Way and open clusters from a chair or with braced elbows
≈ £129 / €115
10x magnification · 50 mm objectives · 5 mm exit pupil
A 10x50 from Pentax’s Jupiter series, listed with a single specification line and nothing else.
Best for: A buyer who already knows the Jupiter series and only needs the reference
≈ $99 / €73
10x · 50 mm · 758 g · waterproof and gas-filled
A waterproof, gas-filled 10x50 with BaK-4 glass, UR coating, twist-up eyecups and a metal centre focuser, published with its weight and dimensions.
Best for: Dusk and astronomy use in weather that would worry an unsealed pair
≈ $166 / £145 / €136
10x · 50 mm · 94 m field at 1000 m · 740 g
A 10x50 with BaK-4 prisms carrying an additional silver mirror coating, published with its field of view, weight, dimensions and close focus.
Best for: The observer who wants to compare figures before buying rather than adjectives
≈ $238 / £181 / €175
12x magnification · 42 mm objectives · 3.5 mm exit pupil
A nitrogen-filled magnesium-bodied 12x42 with BAK4 prisms and fully multi-coated optics, listed with a test-winner claim that names no testing body.
Best for: Daytime wildlife and landscapes, with occasional astronomy from a braced position
≈ €130
Any figure written into the body of this page was true on the day it was written. The amount shown next to each instrument is requested from the retailer as the page loads, and it is that amount, not the text, that stands.
