focal plane
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noun Optics.
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.
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Question 1 of 7
Let’s start with some etymology: What are the origins of the typographical word “bracket”?
First appeared around 1750, and is related to the French word “braguette” for the name of codpiece armor.
First appeared in 1610, based on the French word “baguette” for the long loaf of bread.
First appeared in 1555, and is related to the French word “raquette” for a netted bat.
TAKE THE QUIZ TO FIND OUT 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. 2021
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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
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