| 摘要 |
The varifocal lens has a first lens cluster of positive refractive power, a second lens cluster of negative refractive power and a third lens cluster of positive refractive power, the third lens cluster being arranged fixed relative to the image plane and the second lens cluster being arranged in a displaceable fashion along the optical axis for the purpose of varying the magnification, and the deviation in the image location which is caused by movement of the second lens cluster being compensated by movement of the first lens cluster along the optical axis. Displaceability of the aperture stop along the optical axis is advantageously provided together with the movement of the first lens cluster. In this case, the stop is preferably constructed such that its diameter is varied with the movement along the optical axis. <IMAGE>
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