| 摘要 |
A telephoto lens system of a four-lens-group arrangement includes a negative first lens group, a positive or negative second lens group, a negative third lens group and a positive fourth lens group. The telephoto lens system of the four-lens-group arrangement is constituted by less than six lens elements in total. The positive or negative second lens group is constituted by a positive lens element and a negative lens element which are cemented to each other, in this order from the object. The positive lens element has a convex surface with a larger curvature facing toward the object. The positive or negative second lens group satisfies the following condition: <?in-line-formulae description="In-line Formulae" end="lead"?>0.8<f2p/|f2n|<1.4. (1)<?in-line-formulae description="In-line Formulae" end="tail"?>
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