| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for obtaining a focal distance area at a wider angle than a focal distance at a wide angle end by shortening an internal be tween lens groups and a back focus. SOLUTION: This zoom lens is composed of four lens groups, that is, a 1st group having positive power, a 2nd group, a 3rd group having positive power and a 4th group having negative power, and variable power action is performed by changing space between the 1st group and the 2nd group, space between the 2nd group and the 3rd group and space between the 3rd group and the 4th group. In order to obtain an extended wide angle area independent of the wide angle end, the zoom lens is set to satisfy following conditional expressions. D1 W>D1 WS and D4 W>D4 WS, wherein, D1 W means a real distance between the 1st group and the 2nd group at the wide angle end, D1 WS means a real distance between the 1st group and the 2nd group at the extended wide angle end, D4 W means the back focus of a lens entire system at the wide angle end, and D4 WS is the back focus of the lens entire system at the extended wide angle end.
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