binocular

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Related to binocularly: monocular, binoculars

binocular,

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.

Bibliography

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

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binocular

[bī′näk·yə·lər]
(biology)
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.
(optics)
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 ?
When these images are fused binocularly, observers indicate the coherent direction of dots ('signal') among the random direction dots ('noise').
At his last examination, his best-corrected visual acuity was 20/200 in each eye and binocularly. The patient was not on any glaucoma medications, and IOPs were 13 mmHg in the right eye and 14 mmHg in the left eye.
As shown in Figure 1, two horizontal sine-wave gratings (0.3cycle/[degrees], 6.6[degrees] x 6.6[degrees]) with equal and opposite phase-shift of 22.5[degrees] relative to the centre screen were dichoptically presented to the two eyes; if the patched eye became stronger, the binocularly perceived phase would be more minus; otherwise, if the patched eye became weaker, the binocularly perceived phase would be more positive.
The participant's task was to identify the stimulation test binocularly.
Funduscopy showed a binocularly dull macula area with poor fovea reflex.
For our study, participants were performed both binocularly and monocularly, making us better understand the vision function of the individual participant.
Ocular movements were tested uniocularly and binocularly. Retinoscopic examination was carried out under appropriate cycloplegia.
The test was performed binocularly at the subject's habitual near work distance with correction.
The subjects were instructed to gaze binocularly at each frequency flickering stimulus for 30 s, followed by a rest period of approximately 1-2 min.
All measurements were taken binocularly and the experimental sessions started with the stimulus at suprathreshold levels, after a rehearsal trial to make sure that the task was clearly understood.
Observers performed two different searching tasks in natural binocularly viewing conditions.