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.

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Origin of focal plane

First recorded in 1890–95

Words nearby focal plane

focal glomerulonephritis, focal infection, focalize, focal length, focal necrosis, focal plane, focal-plane shutter, focal point, focal ratio, focal reaction, focal segmental glomerulosclerosis

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2021

Example sentences from the Web for focal plane

Chérif was arrested in Paris in January 2005 as he was about to board a plane to Damascus along with a man named Thamer Bouchnak.
France Mourns—and Hunts|Nico Hines, Christopher Dickey|January 8, 2015|DAILY BEAST
As we waited for my plane to come in, we stayed silent for a long time.
The Story Behind Lee Marvin’s Liberty Valance Smile|Robert Ward|January 3, 2015|DAILY BEAST
And then I got on a plane, and guess what was playing: I Never Sang for My Father.
The Story Behind Lee Marvin’s Liberty Valance Smile|Robert Ward|January 3, 2015|DAILY BEAST
“Call me when the plane leaves the ground,” she said, in a tone that implied she knew her husband well.
Mario Cuomo, a Frustrating Hero to Democrats, Is Dead at 82|Eleanor Clift|January 2, 2015|DAILY BEAST

On Monday, Soelistyo had jolted relatives as well as searchers by suggesting that the plane could be “at the bottom of the sea.”
Wreckage, Bodies of AirAsia Crash Found|Lennox Samuels|December 30, 2014|DAILY BEAST
My two eyes haven't quite the same focal length and this often puts me out of the straight with a column of figures.
The Salvaging Of Civilisation|H. G. (Herbert George) Wells
The sequestered spot, a seat beneath a plane tree, with a lonesome arc-lamp shining full upon it, was occupied.
The Joyous Adventures of Aristide Pujol|William J. Locke
Hence the latter is not level, but has, in places, steps which have been worn to an inclined plane.
The Catacombs of Rome|William Henry Withrow
The observed effect is probably due to the fact that the focal surface is not flat, but curved.
Photographs of Nebul and Clusters|James Edward Keeler
Therefore the families were strong, united, sound, resisting the storm like a line of plane trees!
Frdric Mistral|Charles Alfred Downer

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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focal plane

noun Optics.

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Origin of focal plane

Words nearby focal plane

Example sentences from the Web for focal plane

British Dictionary definitions for focal plane

noun