| 摘要 |
PURPOSE:To set the movement quantity of a movable lens group consisting of a positive and a negative lens and the shift correction quantity of an image in proportional relation and to simplify a driving device by providing a fixed lens group and the movable lens, and setting specific condition between the focal length of the fixed lens and the focal length of the whole system. CONSTITUTION:The fixed lens group I and the movable lens group II consisting of at least one positive lens and one negative lens each which moves at right angles to an optical axis to correct the blurring of an image are provided at right angles to the optical axis. Then the absolute value of the focal length F1 of the lens group I is set >=4 times as large as the focal length FT of the whole system and an on-axis light beam which is incident on the lens group II through the lens group I is decreased. Further, 0.25FT<F2<0.8FT, and 43<nuP and nuN<40 hold for the focal length F2 of the lens group II, and the mean Abbe numbers nuP and nuN of the materials of the positive and negative lenses of the lens group II. Consequently, the movable lens is reduced in size and weight, the response is improved, and the movement quantity and correction quantity become proportional to each other, thereby simplifying the driving device.
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