| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a wide angle lens having high sharpness by avoiding extreme image distortion from a periphery part to the most periphery part by a small number of lenses such as a minimum of four lenses even at a super wide angle, especially, at the viewing angle of about 140°. <P>SOLUTION: In the super wide angle lens constituted of four lenses, a first lens 1, a second lens 2, a third lens 3, an aperture stop 5, and a fourth lens 4 are arranged in this order from an object side, and the first lens 1 and the second lens 2 are negative meniscus lenses whose convex surfaces face the object side, and the third lens 3 and the fourth lens 4 are biconvex lenses, and then at least four or more surfaces of the lens surfaces on the object side from the aperture stop 5 are made aspherical. The fourth lens 4 is formed so that both surfaces are aspherical. When a synthetic focal length from the first lens 1 to the third lens 3 is denoted as f<SB>123</SB>and the focal length of the lens entire system is denoted as f, a conditional expression of -15.0<f<SB>123</SB>/f<-8.0 is satisfied. When the focal length of the fourth lens 4 is denoted as f<SB>4</SB>, a conditional expression of -6.5<f<SB>123</SB>/f<SB>4</SB><-3.0 is satisfied. <P>COPYRIGHT: (C)2009,JPO&INPIT</p> |
