zoom lens

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zoom lens

a lens system that allows the focal length of a camera lens to be varied continuously without altering the sharpness of the image
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Zoom Lens


a combination of a telescopic attachment and an objective lens, forming an optical system with a variable focal length. The mechanical motions of the individual elements of the telescopic attachment ensure that the image scale of an object varies smoothly within a specified range. The focal length of a zoom lens is varied, but the sharpness of focus of the objective and the relative aperture remain unchanged.

Zoom lenses are used most often on motion-picture cameras for creating the illusion that the camera is approaching or receding in cases where it is not desirable to move the camera relative to the object being filmed. Because the aberrations of the telescopic attachment and the objective lens are usually calculated separately, the same attachment may be used with different objective lenses.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

zoom lens

[′züm ¦lenz]
A system of lenses in which two or more parts are moved with respect to each other to obtain a continuously variable focal length and hence magnification, while the image is kept in the same image plane. Also known as variable-focal-length lens; varifocal lens.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
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When considering digital cameras with a zoom lens, what's important is the optical zoom distance and not the digital zoom distance.
The Digital IXUS 110 IS offers the ultimate in wide shooting via a wide-angle zoom lens, wide-aspect LCD and widescreen HD movie shooting, while the Digital IXUS 990 IS delivers superior telephoto reach via a 5.0x optical zoom, and detailed image review with a 3.0" PureColor LCD II.
Incorporating a 2.4X optical zoom lens with 4X digital zoom, the camera has an autofocus system that keeps most of the camera's image plane in sharp focus.
It offers 7.1 mega-pixels, 3x optical zoom lens, 2.5-inch LCD, Bright Capture Technology and digital image stabilization mode.
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It has adjustable frame rates, two built-in digital still cameras, total image control of more than 23 variables of the video image (all independently adjustable), and a Canon 20X zoom Lens with optical image stabilization.
The VB-C50i/VB-C50iR Pan/Tilt/Zoom Network Camera features an advanced 26X optical zoom lens and a 12X digital zoom to enable users to capture fine detail from far distances and crisp 640 x 480-pixel resolution video with up to 30-frames-per-second quality.
For my second example (opposite, top left), I used a telephoto zoom lens set at about 200mm to flatten perspective in this photograph of a row of tombs in a Buddhist cemetery in Pakxe, Laos.