JPS6474517A - Zoom lens - Google Patents

Abstract

PURPOSE:To offer a zoom lens having a large aperture and a high performance, which can realize a small size, light weight and low cost, although its variable power rate is low by constituting a first positive group and a second negative group, of two pieces each which have combined a negative lens and a positive lens, respectively, and making them movable, and fixing a third positive group. CONSTITUTION:The titled zoom lens is constituted of the first group I having positive refracting power, the second group II having negative refracting power, and the third group III having positive refracting power in order from an object side, and at the time of zooming, the first group I moves and keeps the image face constant, the second group II moves for variable power, and the third group III is immobile and brings a divergent luminous flux after being emitted from the second group, to image formation. The first group I consists of a negative meniscus lens being convex to the object side and a biconvex lens whose strong face is turned to the object side, and the second group II consists of a negative lens whose strong face is turned to the image side and a positive meniscus lens being convex to the object side, and a negative lens preceding type, respectively. Although the moving part is constituted of only four pieces, a zoom part of a small size and light weight,whose aberration fluctuation is small at the time of zooming, and whose residual aberration is small even if it is used in a wide view area can be realized.