Binocular telescopes, or binoculars, (also known as field glasses) are two identical or mirror-symmetrical telescopes mounted side-by-side and aligned to point accurately in the same direction, allowing the viewer to use both eyes (binocular vision) when viewing distant objects. Most are sized to be held using both hands, although there are much larger types.
Unlike a monocular telescope, binoculars give users a three-dimensional image: the two views, presented from slightly different viewpoints to each of the viewer's eyes, merge to produce a single perceived view with a sensation of depth, allowing distances to be estimated. There is no need to close or obstruct one eye to avoid confusion, as is usual with monocular telescopes. When using hand-held binoculars the two hands and the head form a steady three-point platform, with less tendency to shake than a single-eye instrument.