| 摘要 |
A compact standard zoom lens having a high performance, composed, in order from the object side, of a front lens group being a divergent lens group and a rear lens group being a convergent lens group. Both lens groups are mechanically movable to vary the focal length. The divergent lens group is composed, in order from the object side, of a first positive lens, a second double concave negative lens and a third positive meniscus lens convex on the object side. The convergent lens group is composed of less than five positive lenses and one negative lens. The zoom lens satisfies the following conditions: 0.7¦r3¦<¦r2¦<0.95¦r3¦r2, r3<0 (1) n2>1.80 (2) d1+d2+d3+d4+d5<0.45 Fs (3) 0.6<r4/r5<1.0, (4) where: Fs is the minimum focal length of the overall zoom lens, ni is the refractive index of the i-th lens at d-line, nu i is the Abbe number of the i-th lens, rj is the radius of curvature of the j-th surface, and dk is the k-th lens thickness or lens distance.
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