| 摘要 |
PROBLEM TO BE SOLVED: To provide a telephoto zoom lens which is capable of quick focusing and has satisfactory optical performance. SOLUTION: The telephoto zoom lens comprises a first lens group having a positive refracting power, a second lens group having a negative refracting power, a third lens group having a positive refracting power, and a fourth lens group having a positive refracting power in this order from the object side. The first lens group and the fourth lens group are fixed to the optical axis and the second lens group moves on the optical axis toward an image surface when magnifications are varied from a wide angle end to a telephoto end. The first lens group comprises three groups, that is, a 1A-th lens group having a positive refracting power, a 1B-th lens group having a negative refracting power, and a 1C-th lens group comprising a single positive lens or including at least one negative meniscus lens and having a positive refracting power, in this order from the object side. The 1C-th lens group is moved in the direction of the optical axis to perform focusing. COPYRIGHT: (C)2004,JPO
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