Patent ID: 6563642
Filing Date: 2003-05-13
Classification: G02B

Abstract:
A binocular comprising, in order from an object side to an observation side:a pair of objective optical systems of which focal lengths vary respectively; a pair of erect optical systems; and a pair of eyepiece optical systems for observing a pair of object images respectively formed through said pair of objective optical systems, wherein each one of said objective optical systems has a plurality of lens units including a first lens unit which (a) is located closest of the plurality of lens units to the object side of said objective optical system, (b) is of a positive refractive power, and (c) consists of a cemented lens composed of, in order from the object side, a positive lens and a negative lens, and wherein each one of said pair of objective optical systems satisfies the following condition: 0.7where &bgr;t is an overall lateral magnification in a telephoto end of each one of said pair of objective optical systems excluding said first lens unit.