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small optical instrument consisting of two similar telescopestelescope,
traditionally, a system of lenses, mirrors, or both, used to gather light from a distant object and form an image of it. Traditional optical telescopes, which are the subject of this article, also are used to magnify objects on earth and in astronomy; other types of
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 mounted on a single frame so that separate images enter each of the viewer's eyes. As with a single telescope, distant objects appear magnified, but the binocular has the additional advantage that it substantially increases the range of depth perception of the viewer because the magnified images are seen with both eyes. The frame of a binocular is usually hinged to permit adjustment of the distance between the telescopes. Focusing can be done by means of a wheel on the central axis between the telescopes; turning the wheel changes the distance from the objective lenses of the telescopes to the eyepieces. Separate focusing of each telescope from the eyepiece may be provided in some types of binocular. The term binocular now usually refers to the prism binocular, in which light entering each telescope through its objective lens is bent first one way and then the other by a pair of prisms before passing through one or more additional lenses in the eyepiece. The prisms aid in reducing the length of the instrument and in enhancing the viewer's depth perception by increasing the distance between the objective lenses. Other types of binocular include the opera glass and the field glass; both use Galilean telescopes, which do not employ prisms and which usually have less magnifying power than the telescopes in prism binoculars. A binocular is often specified by an expression such as "7×35" or "8×50"—the first number indicates how many times the binocular magnifies an object and the second number is the diameter of either objective lens in millimeters. The size of an objective lens is a measure of how much light it can gather for effective viewing.


See J. T. Kozak, Deep-Sky Objects for Binoculars (1988).

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Of, pertaining to, or used by both eyes.
Of a type of visual perception which provides depth-of-field focus due to angular difference between the two retinal images.
Any optical instrument designed for use with both eyes to give enhanced views of distant objects, whose distinguishing performance feature is the depth perception obtainable.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
The association between nonstrabismic anisometropia, amblyopia, and subnormal binocularity. Ophthalmology.
As I understand it, then, binocularity assumes a distinction between public and private morality (between "cultural and individual values," in Parens and Johnston's language).
Binocularity is highly dependent upon the efficiency of the fourteen muscles of the eyes as well as the two sides of the brain.
This applied to both binocularity and orientation selectivity.
They engage the greater tensions of depth of field, monocularity and binocularity that seem to mark the naturalistic style of Regeneration.
The cover test is not repeated during the usual school vision screening and no tests of binocularity or hyperopia are performed.
Despite being referred for OK fitting, Ajay's BV status made him an unsuitable candidate, so he has stayed in spectacle correction for the year since, with both prism correction for fusion and vision training provided to improve his binocularity. While a -0.50D shift in both eyes has occurred over this subsequent year, this is much less than the year prior and as the sensory component of Ajay's strabismus has improved, in time he may be suitable to be fitted with OK or another soft myopia controlling contact lens.
report that patients with similar strabismus diagnoses may exhibit different types of abnormal head position (AHP) and that patients may develop amblyopia or lack binocularity despite AHP.
(4) High refractive errors in childhood may lead to amblyopia, subnormal binocularity or strabismus resulting in permanent visual loss if not corrected during early childhood.
Possible explanation is that binocularity and parallelism are maintained by the extraocular muscles under the controlling influence of fusion.
His research on colour and binocularity is outlined, together with those of other students of vision in that century.