| 摘要 |
PROBLEM TO BE SOLVED: To provide a wide angle lens which is made small-sized and light-weight and can be manufactured, at low cost, and which has a long exit pupil. SOLUTION: The lens optical system 100 of the wide angle lens includes a first group lens 10, having negative power and a second group lens 20 having positive power which are arranged in order from an object side. The second group lens 20 includes a front group lens 30, arranged on the object side across a diaphragm 5 and a rear group lens 40 arranged on the opposite side across the diaphragm 5. At least three of the lens surfaces of the lens groups constituting the entire lens system are aspheric. The wide-angle lens satisfies conditional expressions (1) to (3): 0.5<fm/fR<3.0 (1),νdm<45 (2), 0.5<¾F1/F2¾<3.0 (3), wherein F1 is the focal length of the first group lens 10, F2 is the focal length of the second group lens 20, fm is the focal length of the front group lens 30, fR is the focal length of the rear group lens 40, andνdm is the Abbe number of the front group lens 30. COPYRIGHT: (C)2009,JPO&INPIT
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