| 摘要 |
PROBLEM TO BE SOLVED: To make variable power higher and an angle wider, while securing miniaturization. SOLUTION: In a positive, negative, positive and positive four-group lens configuration, a first lens group G1 is configured in such a manner that a negative lens whose concave surface faces an image side and a positive lens whose convex surface faces an object side are arranged, in this order starting from the object side to the image side, and a second lens group G2 is configured, in such a manner that a negative lens whose concave surface faces the image side; anda biconcave negative lens whose concave surfaces face the object side and the image side, and a meniscus positive lens whose convex surface faces the object side are arranged, in this order starting from the object side to the image side. The surface on the object side of the negative lens and the surface on the image side of the positive lens, which are arranged on the object side in the second lens group are aspherical. A conditional expression (1) is satisfied, the conditional expression (1) being 2.0<f1/(fw×ft)<SP>1/2</SP><2.5, where f1 represents the focal length of the first lens group, fw represents the focal length of the entire lens system at the wide-angle end, and ft represents the focal length of the lens system as a whole at the telephoto end. COPYRIGHT: (C)2011,JPO&INPIT
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