3x50 wide-field stargazing binoculars

What constellation binoculars are for

Most binoculars are made to bring distant things closer. Constellation binoculars do the opposite job: they keep the magnification low so the field of view stays huge. This pair is marked 3x50 with a 17 degree field. For comparison, a typical 10x50 shows around 5 to 7 degrees, and the bowl of the Plough is roughly 10 degrees across.

The result is a view that looks like the naked-eye sky, only with more stars. Star clouds in the Milky Way, the Pleiades with the stars around them, the belt and sword of Orion and the W of Cassiopeia fit into the field with room to spare. Because the magnification is so low, the view stays steady in your hands.

An honest note on brightness

The exit pupil of a 3x50 is 50 / 3 = 16.7 mm, much wider than the pupil of any human eye, which opens to about 7 mm at most in the dark. Your eye can only use the part of the beam that fits through your pupil, so in practice you do not get the full light grasp of a 50 mm lens. What you gain is the field of view and the easy, steady view, not the brightness of a pair of 10x50s. For the Moon's craters, Jupiter's moons and fainter clusters, use a 10x50 or the 12x50 on a tripod.

Getting the most from them

Use them from the darkest place you can reach, away from street lights, and give your eyes at least 20 minutes to adapt. Sweep slowly along the Milky Way in late summer and autumn, or across Orion and Taurus in winter. A planisphere or a star chart app on a red screen setting helps you find your way. Binoculars for stargazing explains how to choose and use binoculars for the night sky.