Konica Corporation

Konishiroku Photo Industry Co., Ltd.

Minoru Yokota

Kohei Ota

Masae Sato

Masamichi Kitagawa

A zoom lens to form an image of an object with variable magnification, is provided with a first lens group having a positive refracting power, and a second lens group positioned closer to the image than the first lens group and having a negative refracting power. When the magnification is changed, a distance between the first lens group and the second lens group is changed. The first lens group comprises a 1-1 lens, a 1-2 lens and a 1-3 lens aligned in this order from the object. The zoom lens comprises at least two plastic lenses.

Zoom lens

Zoom lens having two lens groups

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:

Copying lens

In a lens system of five groups of five lens elements in which a front group of two lens elements and a back group of two lens elements are symmetrically arranged on either side of a biconvex lens centrally located therebetween, a copying lens characterized in that the lens elements in sequence from the object comprise a first lens having a positive meniscus configuration with its convex surface directed toward an object, the second lens having a biconcave configuration, a third lens having a biconcovex configuration, a fourth lens having a biconcave configuration and a fifth lens having a positive meniscus configuration with its convex surface being directed toward the image and in which the condition

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Hachioji, Japan

Minoru Yokota