focal plane

nounOptics.

a plane through a focal point and normal to the axis of a lens, mirror, or other optical system.: Compare principal plane.
the transverse plane in a telescope where the real image of a distant view is in focus.

Origin of focal plane

First recorded in 1890–95

Words Nearby focal plane

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use focal plane in a sentence

The total movement of the half-object glass is double the distance between the star images in the focal plane.
History of Astronomy | George Forbes
Rays of light from some distant object are converged by the objective (D) and form an inverted image (ab) at the focal plane (F).
Visual Signaling | Signal Corps United States Army
If any error of convexity exists in the plate, the focal plane is disturbed, and the eyepiece must be moved out.
Scientific American Supplement, No. 484, April 11, 1885 | Various
The photographer must change the plate, set the focal plane shutter, and press the release.
America's Munitions 1917-1918 | Benedict Crowell
The focal plane of the light is elevated 93 ft. above high water.
Encyclopaedia Britannica, 11th Edition, Volume 16, Slice 6 | Various

British Dictionary definitions for focal plane

focal plane

noun

the plane that is perpendicular to the axis of a lens or mirror and passes through the focal point
the plane in a telescope, camera, or other optical instrument in which a real image is in focus

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

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