| 摘要 |
PROBLEM TO BE SOLVED: To provide a wide-angle monofocal lens made compact and realizing the simplification of constitution. SOLUTION: The wide-angle monofocal lens is equipped with a 1st lens G1 which is a meniscus turning its concave surface toward an object side, a 2nd lens G2 the object-side surface of which is formed to be convex and which has positive power, a 3rd lens G3 which is a meniscus turning its convex surface toward an image surface side and which has positive power, and a 4th lens G4 which is a meniscus turning its concave surface toward the image surface side in order from the object side, and satisfies following conditional expressions (1) to (4). (1): 10.0<¾f1/f¾, (2): 2.0<¾f4/f¾<10.0 (3): 1.45<Nd<1.60 and (4): 50.0<νd<60.0 provided that (f) means the focal distance of the whole, f1 and f4 mean the focal distances of the 1st lens G1 and the 4th lens G4, and Nd andνd mean the refractive index and the Abbe number of each of the 1st to the 4th lenses G1 to G4 on a d-line. COPYRIGHT: (C)2004,JPO&NCIPI
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