| 摘要 |
PROBLEM TO BE SOLVED: To provide a photographic lens whose telecentricity is satisfactorily corrected though its miniaturization is achieved further than in the conventional manner in a triplet lens where an aperture diaphragm is arranged nearest to an object side. SOLUTION: In the photographic lens where the aperture diaphragm 1, a first lens L1, a second lens L2 and a third lens L3 are arranged in this order from the object side, the first lens L1 is a positive meniscus lens turning its convex surface to the object side, the second lens L2 is a meniscus lens turning its convex surface to an image side, and the third lens L3 is a meniscus lens turning its convex surface to the object side, and the first, the second and the third lenses L1, L2 and L3 are formed of plastic lenses whose both surfaces are aspherical. The photographic lens satisfies conditional expressions: -0.20<f/f<SB>2</SB><0.15 and -0.25<f/f<SB>3</SB><0.20 when assuming that f is the focal distance of an entire system, f<SB>2</SB>is the focal distance of the second lens, and f<SB>3</SB>is the focal distance of the third lens. COPYRIGHT: (C)2007,JPO&INPIT |
