| 摘要 |
PROBLEM TO BE SOLVED: To provide a wide angle lens suitable for a thin high-pixel imaging device. SOLUTION: This wide angle lens is composed of a 1st lens 1 having negative refractive power and having biconcave shape whose concave surface on the object side is made aspherical, a 2nd lens 2 having positive refractive power, a 3rd lens 3 having negative refractive power and having biconcave shape whose concave surface on the object side has a large curvature, a 4th lens 4 combined with the 3rd lens 3 and having positive refractive power, and a 5th lens 5 having positive refractive power and having a convex surface consisting of an aspherical surface on the object side, in this order from the object side to an image surface side, and satisfies 0.7<|f1|/f<3, 0.8<|f1|/|f2|<2,|f1x2|/|f3x4x5|>1.8, (D1+D2+D3)/f<2, 0.7<|R6|/|R8|<1.5,ν1>ν2 andν3<ν4 (provided that f, f1 , f2 , f1x2 and f3x4x5 are the focal distances of the respective lenses, D1, D2 and D3 are axial surface spaces, R6 and R8 are the radii of curvature andνi is an Abbe number). Thus, the thin wide angle lens is obtained.
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