| 摘要 |
PROBLEM TO BE SOLVED: To provide a zoom lens with a vibration-proof function capable of maintaining a good optical performance all over the variable power range of a four- group zoom lens subjected to vibration and to provide optical equipment using the zoom lens. SOLUTION: The zoom lens is provided with a 1st group having positive refractive power, a 2nd group having a power-varying function and negative refractive power, a 3rd group having positive refractive power and a 4th group having positive refractive power in this order from the object side. The 1st group is constituted of a group 1A and a group 1B having positive refractive power, and at varying the power from a wide angle end to a telephoto end, the group 1A is fixed, and the group 1B is fixed or moved, the 2nd group is moved toward an image surface, the 3rd group is moved and the 4th group is fixed, and at focusing, the group 1B is actuated to focus, and part or all of the 2nd group is moved in a direction nearly vertical to the optical axis so as to correct the blurring of an image, and the focal distance fi of an i-th group, the focal distance fW of the whole system at the wide angle end, the focal distance fT of the whole system at the telephoto end, the moving extent M1B of the group 1B and the moving extent M2 of the 2nd group in accordance with the power variation are appropriately set. |
