| 摘要 |
PROBLEM TO BE SOLVED: To provide a zoom lens by which flare is effectively eliminated, while simplifying a lens barrel mechanism by integrating an aperture diaphragm and a flare-cut diaphragm. SOLUTION: This zoom lens possesses a first lens group G1 of negative refracting power, an aperture diaphragm SP1, a second lens group G2 of positive refracting power and the flare-cut diaphragm SP2, and at varying of power from a wide angle end to a telephoto end, the second lens group G2 is moved to the object side and the first lens group G1 is moved nonlinearly, so that the fluctuation of an image surface position due to the variable power is corrected. The aperture diaphragm SP1 and the flare-cut diaphragm SP2 are moved by an appropriate quantity to the object side as an integrated structure. The aperture diaphragm SP1 is set at an appropriate position for an intermediate viewing angle focal distance from the wide angle end, so that the flare of a lower light beam is eliminated effectively. The flare-cut diaphragm SP2 is arranged at the appropriate position for the intermediate viewing angle focal distance, so that the flare of an upper light beam is cut.
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