| 摘要 |
PROBLEM TO BE SOLVED: To provide a three-group zoom lens which enables making of an attempt to accomplish miniaturization and cost reduction while maintaining superior optical performance. SOLUTION: In the three-group zoom lens having negative power, positive power, and positive power in order from an object side, a first lens group G1 is built from a first negative lens L1 and a second positive biconvex lens L2 which is formed from a plastic material and which has at least one aspherical surface; a second lens group G2 is built from a positive, a negative cemented lens L34 and a fifth lens L5 assuming a meniscus shape; and a third lens group G3 is built from a sixth lens L6 which is a positive single lens. The zoom lens fulfills conditional expressions provided below: (1) 3.2<fg<SB>2</SB>/fw, (2) 26<ν<SB>1</SB>-ν<SB>2</SB><30, (3) D<SB>1</SB>/fw<0.75 (fg<SB>2</SB>: a focal length of the second lens, fw: a focal length of an entire system achieved at a wide-angle end,ν<SB>1</SB>: Abbe number of the first lens,ν<SB>2</SB>: Abbe number of the second lens, and D<SB>1</SB>: Axial distance from a lens surface most closely positioned to the object side to a lens surface most closely positioned to an image side in the first lens group). COPYRIGHT: (C)2009,JPO&INPIT
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