| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an imaging lens system having high aberration correction capabilities regardless of the presence or absence of an attachment lens. Ž<P>SOLUTION: The imaging optical system lens 110 includes, in order from the incident side of image light, a diaphragm 111, a first group lens 112, a second group lens 113, and a third group lens 114. The first group lens 112 is a concave lens formed of a cemented lens composed of a first lens L1 and a second lens L2. The second group lens 113 is a non-spherical convex lens. The third group lens 114 is a concave lens. The imaging optical system having a three-group four-lens configuration satisfies the following conditional expressions 1 and 2: <Conditional expression 1> 0.48≤f2/f≤0.80, wherein f is the focal distance of the imaging optical system and f2 is the focal distance of the second group lens; and <Conditional expression 2> 0.23≤V1/V2≤0.95, wherein V1 is the Abbe's number of the first lens of the first group lens and V2 is the Abbe's number of the second lens of the first group lens. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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