| 摘要 |
A zoom lens of high image quality having various aberrations improved and most suitably used with a still camera is disclosed. A first lens group (Gr1) to a fifth lens group (Gr5) having positive, negative, positive, positive and substantially zero refracting powers, respectively, are arranged in that order from an object side toward an image surface side. The third lens group (Gr3) is configured of a joint lens of a convex lens and a concave lens, while the fifth lens group is configured of a joint lens of a concave lens and a convex lens. The conditions -0.018<1/ upsilon 3<0.018, 10<| upsilon 5.1- upsilon 5.2| and 1<|r5.2/fWxtan omega W|<3 are satisfied, where upsilon 3 is the equivalent Abbe's number of the third lens group, upsilon 5.1 is the Abbe's number of the lens of the fifth lens group nearer to the object side, upsilon 5.2 is the Abbe's number of the lens of the fifth lens group nearer to the image surface side, r5.2 is the radius of curvature of the lens joint surface of the fifth lens group, fW is the focal length of the whole lens system at the wide angle edge, and omega W is the half field angle at the wide angle edge.
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