focal length
noun Optics.
the distance from a focal point of a lens or mirror to the corresponding principal plane. Symbol: f
the distance between an object lens and its corresponding focal plane in a telescope.
Words nearby focal length
Origin of focal length
First recorded in 1745–55
Also called focal distance.
Dictionary.com Unabridged
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for focal distance
focal length
focal distance
noun
the distance from the focal point of a lens or mirror to the reflecting surface of the mirror or the centre point of the lens
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
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Medical definitions for focal distance (1 of 2)
focal distance
n.
focal length
Medical definitions for focal distance (2 of 2)
focal length
n.
The distance from the surface of a lens or mirror to its focal point.focal distance focus
The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
Scientific definitions for focal distance
focal length
[ fō′kəl ]
The distance between the optical center of a lens or mirror to its focal point.
The American Heritage® Science Dictionary
Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Cultural definitions for focal distance
focal length
The distance between the focal point of a lens (that is, the point at which the lens will focus parallel rays of light) and the lens itself.
The New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.