| 摘要 |
PROBLEM TO BE SOLVED: To maintain superior optical performance, with mass production taken into consideration and with thickness DL of a lens system kept in a prescribed range, while reduction in a total length is attained. SOLUTION: The imaging lens includes a positive first lens L1 in which an object side face is a convex near the optical axis, a negative second lens L2 in which an image side face is a concave near the optical axis, a third lens L3 having negative power near the optical axis, and a fourth lens L4 in which the two faces are aspherical and in which the image side face is a convex in the periphery. The imaging lens also satisfies the following conditional expressions, where f is the whole focal distance, f3 is the focal distance of the third lens L3, and DL is a thickness of the lens system. (1) is expressed as -1.5≤f/f3≤-0.005 and (2) as 0.80≤DL/f≤0.97. COPYRIGHT: (C)2009,JPO&INPIT
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