equivalent focal length

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noun

optics the ratio of the size of an image of a small distant object near the optical axis to the angular distance of the object in radians

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Words nearby equivalent focal length

equivalence relation, equivalency, equivalent, equivalent air speed, equivalent circuit, equivalent focal length, equivalent weight, equivalve, equivocal, equivocally, equivocate

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

How to use equivalent focal length in a sentence

The equivalent focal length of a negative or Huygens eyepiece is equal to half the focal length of the larger or field lens.
Pleasures of the telescope|Garrett Serviss
When the simple67 expression "focal length" is used, it always refers to the equivalent focal length.
The Barnet Book of Photography|Various