| 摘要 |
PROBLEM TO BE SOLVED: To provide a superwide angle imaging optical system having a superwide viewing angle in a horizontal direction, a suppressed viewing angle in a vertical direction and comparatively reduced image distortion. SOLUTION: The superwide angle imaging optical system 10 comprises a first lens group 20, a diaphragm 40, a second lens group 30, a cover glass 51, and an imaging element 52 which are arrayed in order from the object side. The first lens group 20 includes a negative meniscus lens convexed to the object side, a negative lens and a negative lens which are arrayed in order from the object side and the second lens group 30 includes a plurality of positive lenses. Further, the first lens group 20 and the second lens group 30 include lenses each having an anamorphic surface. When it is assumed that horizontal optical power is Ph, vertical optical power is Pv, a horizontal focal distance in the whole system of the superwide angle imaging optical system 10 is fh, and a vertical focal distance is fv, the lens including the anamorphic surface is constituted so as to satisfy a conditional expression of -0.6<(Ph-Pv)*(fh+fv)<-0.1. COPYRIGHT: (C)2007,JPO&INPIT
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