range finder


range finder

noun

Definition of RANGE FINDER

1
:  an instrument used in gunnery to determine the distance of a target
2
:  a surveying instrument (as a transit) for determining quickly the distances, bearings, and elevations of distant objects
3
:  a usually built-in adjustable optical device for focusing a camera that automatically indicates the correct focus (as when two parts of a split image are brought together)

First Known Use of RANGE FINDER

1872

range finder

noun    (Concise Encyclopedia)

Instrument used to measure the distance from the instrument to a selected point or object. The optical range finder, used chiefly in cameras, consists of an arrangement of lenses and prisms set at each end of a tube. The object's range is determined by measuring the angles formed by a line of sight at each end of the tube; the smaller the angles, the greater the distance, and vice versa. Since the mid-1940s, radar has replaced optical range finders for most military targeting, and the laser range finder, developed in 1965, has largely replaced optical range finders for surveying and radar in certain military applications.

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