Patent ID: 6995928

Claim:
A wide angle optical system for a solid image pickup element, comprising an image pickup lens, and a diaphragm disposed on a side of the image pickup lens closer to an object, wherein said image pickup lens is a biconvex lens, its surface on a side closer to an image surface being formed into such an aspherical shape that the positive refractive power is weaker at a location more spaced in a diametrical direction apart from an optical axis, and the image pickup lens satisfies the following condition expression (1): 1.3 ≧|r 1 /r 2 |≧0.8 (1) wherein r 1 is a radius of curvature of the surface of the image pickup lens closer to the object, and r 2 is a radius curvature of the surface of the image pickup lens closer to the image surface; and wherein said image pickup lens satisfies the following condition expression: 0.4≧ SH/fl ≧0.2 (4) wherein SH is a distance from a main point on a front side of the image pickup lens to the diaphragm.