| 摘要 |
PROBLEM TO BE SOLVED: To obtain a wide converter lens which has a front element with a small diameter, a compact whole lens system, and gives an excellent optical performance having a small overall aberration when mounted on the object side of a main lens system. SOLUTION: The wide converter lens is mounted on the object side of the main lens system. A negative first lens having a concave face toward the object side is arranged on the side nearest to the object, a positive second lens is arranged on the image side of the first lens, and a negative third lens is arranged on the image side of the second lens. The converter lens is characterized in satisfying the condition 1.0<(r1-r2)/(r1+r2)<2.0-40<f1/D<-7, where the radii of curvature of the object side and the image side faces of the first lens are denoted by r1 and r2, respectively, the focal length of the first lens is denoted by f1, and the air space distance between the second lens and the third lens is denoted by D. COPYRIGHT: (C)2008,JPO&INPIT
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