| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a zoom lens which combines a zoom range having a constant bright open F number and high magnification promotion with each other. Ž<P>SOLUTION: In the zoom lens, a stop 2 moves in an optical axis direction during zooming, a position of the stop in a telephoto end is located on an object side with respect to a position of the stop in a wide-angle end; an opening size of the stop is controlled in conjunction with the zooming, so that an open F number becomes approximately constant in a range from the wide-angle end to a specific intermediate focal length; the opening size of the stop is made approximately constant in a range from the specific intermediate focal length to the telephoto end, so that the open F number is changed; and the specific intermediate focal length fulfills a conditional expression (1): wide-angle end focal length×1.5 < specific intermediate focal length < telephoto end focal length/1.4. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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