| 摘要 |
A projection objective with variable focal length is provided, consisting of a front member (F) with negative refractive power and a multiple-lens basic objective (G) with positive refractive power, between which a multiple-lens variator (V) displaceable in the direction of the optical axis and with positive refractive power is disposed, with said objective having seven self-contained lenses (L1-L7) separated from each other by air spaces and free of cemented surfaces, whereof the front member (F) consists of one single lens (1) with negative refractive power, the basic objective consists of a Cookes or Taylor lens (L5, L6, L7) and the variator (V) likewise consists of a Cookes or Taylor lens (L2, L3, L4).
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