| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical system, which can reduce its thickness while having a high variable power ratio and reduces influence of eccentricity to prevent deterioration in performance, and to provide an imaging device using the optical system. SOLUTION: The optical system includes: a first lens group G1 having negative refractive power; a second lens group G2 having positive refractive power; and a cemented lens having positive refractive power as a whole and having cemented surfaces on the optical axis. Lenses constituting the cemented lens satisfy an expression (5): 40<νmax-νmin<80 and an expression (6): 23.7>νmin. In the expressions (5) and (6),νmax is a maximum Abbe number in the cemented lens, andνmin is a minimum Abbe number in the cemented lens. COPYRIGHT: (C)2011,JPO&INPIT
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