Variable power lens system for copying

摘要

A variable power lens system capable of both enlargement and reduction of the image of an original to be copied, in which the distance between the object and image surfaces constant. The lens system includes a first lens group having a first positive focal length and a second lens group having a negative focal length. The distance between the first and second lens groups is variable. A lens power of each lens group is increased so that a distance between the object surface and the lens is long in comparison with a distance between the lens and the image surface and at the same time the variable power ratio is greater than 2 with high performance and compactness.