Try Our Apps


Is irregardless a word?

equivalent focal length

(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
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
Cite This Source
Examples from the Web for equivalent focal length
Historical Examples
  • 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.

Word of the Day

Word Value for equivalent

Scrabble Words With Friends

Nearby words for equivalent focal length