| 摘要 |
A rear-focus, four-lens-group zoom lens has 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. The first, second, third, and fourth lens groups are successively arranged in the order named from an object side. The first and third lens groups are fixed in position. The second lens group is movable for varying magnification and the fourth lens group is movable for compensating for an image plane movement due to the varied magnification and also for focusing. The fourth lens group comprises a negative-meniscus lens having a convex surface directed toward the object side and a positive lens, the negative-meniscus lens and the positive lens being successively arranged in the order named from the object side. The negative-meniscus lens and the positive lens can be either joined to or separated from each other, at least one of the negative-meniscus lens and the positive lens being made of an organic material.
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