focal plane
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
1Words 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 ForbesRays 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 ArmyIf any error of convexity exists in the plate, the focal plane is disturbed, and the eyepiece must be moved out.
The photographer must change the plate, set the focal plane shutter, and press the release.
America's Munitions 1917-1918 | Benedict CrowellThe focal plane of the light is elevated 93 ft. above high water.
British Dictionary definitions for focal plane
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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