Copying lens

摘要

A copying lens system of three lenses is provided in which the total length is less than 0.15f with aberration fully corrected. This is brought about by a three-lens system in which the first lens is a positive meniscus whose convex surface faces the object side, a negative second lens with a concave surface at both ends, and a positive third lens with a convex surface at both ends, the rear surface being a reflection surface. The dimension of the lenses must satisfy the following condition: 5f<¦r6¦<8f and 0.5f<r2<2f wherein f represents the composite focal length of the total system, r2 represents the radius of curvature of the surface of the lens that stands second from the object side, and r6 represents the radius of curvature of the surface of the lens that stands sixth from the object side.