Patent ID: 6310732
Filing Date: 2001-10-30
Classification: G02B

Abstract:
A power-variable finder comprising, successively from an object side, a first lens group having a negative refracting power, a second lens group, movable on an optical axis, having a positive refracting power, and a third lens group having a negative refracting power; said finder satisfying the following conditional expressions (1) to (3):-1.3<f.sub.2 /f.sub.1 <-1.0 (1)1.6<f.sub.3 /f.sub.1 <2.2 (2)-2.4<D.sub.T /f.sub.1 <-1.7 (3)wheref.sub.1 is the focal length of the first lens group;f.sub.2 is the focal length of the second lens group;f.sub.3 is the focal length of the third lens group; andD.sub.T is the distance on the optical axis between the surface closest to the object in the first lens group and the surface closest to an eye in the third lens group, andwherein said first lens group consists of a single negative lens having at least one aspheric surface and having a concave surface directed onto the eye side, said second lens group consists of a single biconvex lens having at least one aspheric surface, and said third lens group consists of a single negative lens.