| 摘要 |
A wide-angle optical system comprises, in order from its object side, a stop, a first lens (L1) having positive refracting power, a second lens (L2) having negative refracting power and a third lens (L3) that is an aspheric lens. The third lens is configured such that as viewed in a lens section including an optical axis, a portion thereof near the optical axis is in a meniscus shape convex on an object side thereof, and an object side surface and an image side surface thereof at a peripheral site are in a meniscus shape convex on an image side thereof. The optical system satisfies the following conditions (1-1) and (1-2). −0.40<f/f3<0.15  (1-1) 0.30<hc7/hp7<2.0  (1-2) where f is the focal length of the whole wide-angle optical system, and f3 is the focal length of the third lens. When Lm stands for a light ray passing through the center of the stop at an angle of 36° with the optical axis, and Pm7 stands for a point at which Lm passes the image side surface of the third lens, hc7 is supposed to be a distance from Pm7 to the optical axis, and hp7 is supposed to be a distance from a convex apex Pp7 of the image side surface of the third lens to the optical axis.
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