Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
262 words
A large aperture zoom lens comprising, from the direction of the object to be photographed, a first lens group for focusing and consisting of a positive compound lens having a negative meniscus lens and a biconvex lens and of a positive meniscus lens convex toward the object, a second lens group for variation and consisting of a negative lens and a negative compound lens having a biconcave lens and a positive lens, a third group for compensation consisting of a positive lens, said third group being movable to and fro for zooming, a fourth group for image forming and consisting of two positive lenses convex toward the object and a biconcave lens as well as a biconvex lens and a positive compound lens having a biconvex lens and a biconcave lens, said fourth group having the longest lens spacing between said biconcave lens and biconvex lens, said large aperture zoom lens satisfying the following conditions: |R 1 | > |R 3 | |r 14 | > |r 16 | |r 20 | > |r 21 | 2.2 f iv > |r 23 | > 1.5 f iv wherein F IV is the focal length of the fourth lens group, R 1 r 3 the radii of the outer surfaces of the positive compound lens in the first lens group, R 14 and R 16 , the radii of the surfaces facing the object in the positive lenses of the fourth lens group, R 20 and R 21 , the radii of the surfaces of the biconvex lens in the fourth lens group.
Claim 2
Dependent Claim
262 words
A large aperture zoom lens comprising, from the direction of the object to be photographed, a first lens group for focusing and consisting of a positive compound lens having a negative meniscus lens and a biconvex lens and of a positive meniscus lens convex toward the object, a second lens group for variation and consisting of a negative lens and a negative compound lens having a biconcave lens and a positive lens, a third group for compensation consisting of a positive lens, said third group being movable to and fro for zooming, a fourth group for image forming and consisting of two positive lenses convex toward the object and a biconcave lens as well as a biconvex lens and a positive compound lens having a biconvex lens and a biconcave lens, said fourth group having the longest lens spacing between said biconcave lens and biconvex lens, said large aperture zoom lens satisfying the following conditions: |R 1 | > |R 3 | |r 14 | > |r 16 | |r 20 | > |r 21 | 2.2 f iv > |r 23 | > 1.5 f iv wherein F IV is the focal length of the fourth lens group, R 1 r 3 the radii of the outer surfaces of the positive compound lens in the first lens group, R 14 and R 16 , the radii of the surfaces facing the object in the positive lenses of the fourth lens group, R 20 and R 21 , the radii of the surfaces of the biconvex lens in the fourth lens group.
Claim 3
Dependent Claim
34 words
A large aperture zoom lens in accordance with claim 1, in which a fine space is provided between the biconvex lens and the biconcave lens forming said positive compound lens of the fourth group.