| 摘要 |
A behind stop wide angle lens system comprises a negative meniscus lens L1 having a convex surface directed to the object, a positive meniscus lens L2 having a convex surface directed to the object, a double-side-concave negative lens L3 having both surfaces concaved, a double-side-convex positive lens L4 having both surfaces convexed, and a stop S. These lenses are arranged in the mentioned order from the end adjacent the object. The lenses satisfying the following conditions (1) to (4): -2.8f<f1<-1.3f (1) 0.7f<f2<0.82f (2) 1.5<r1/r2<2.3 (3) 0.13<r3/r4<0.4 (4) wherein f represents the focal distance of the whole lens system, f1 represents the focal distance of the negative meniscus lens L1, f2 represents the focal distance of the positive meniscus lens L2, r1 and r2 respectively represent the radii of curvature of the object-side surface and the image-side surface of the negative meniscus lens L1, and r3 and r4 respectively represent the radii of curvature of the object-side surface and the image-side surface of the positive meniscus lens L2. With this arrangement, it is possible to obtain a wide view angle while attaining superior image forming performance.
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