| 摘要 |
<P>PROBLEM TO BE SOLVED: To obtain a super-wide angle lens system capable of maintaining high performance, even in actual use, regardless of a compact and inexpensive super-wide angle lens system. <P>SOLUTION: The super-wide angle lens system comprises, in order from an object side, a first lens group G1 having negative refractive power, an aperture diaphragm S, and a second lens group G2 having positive refractive power. The first lens group G1 comprises, in order from the object side, three lenses of a negative meniscus lens 11 convex to the object side, a meniscus lens 12 convex to the object side, and a positive lens 13. The second lens group G2 comprises, in order from the object side, three lenses of a cemented lens of a negative lens 21 and a positive lens 22 and a positive lens 23. The super-wide angle lens system satisfies the following conditional expressions (1) and (2), -1.45<f12/f<-1.15 (1) and 1.4<SF2<2.4 (2), where f12 is the composite focal length of two negative meniscus lenses 11 and 12 in the first lens group, f is the focal length of the entire system, and SF2 is the shaping factor of the negative meniscus lens 12 on an image side in the first lens group. <P>COPYRIGHT: (C)2013,JPO&INPIT |
