equivalent focal length
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equivalent focal length
n
(General Physics) 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 and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
equivalent focal length
The distance measured along the optical axis of the lens from the rear nodal point to the plane of best average definition over the entire field used in a camera. See also focal length.
Dictionary of Military and Associated Terms. US Department of Defense 2005.