| 摘要 |
A front zoom system and a rear zoom system are coupled in said order from an object side, wherein said rear zoom system comprises a fixed positive lens group, a negative compensator lens group in which its first plane has its convex plane facing an object side and its last plane has its concave plane facing an image side, a negative variator lens group in which the lens group itself is virtually achromated, and a fixed relay lens group, being positioned in the order given from an object side. While the magnification variation range is enlarged by consecutively performing the zooming operation of the front zoom system and the zooming operation of the rear zoom system, aberrations at that time are satisfactorily corrected. The focal distance of the variator lens group is made short in comparison with that of the compensator lens group, thus the amount of shifting of this lens group is reduced for making the rear zoom system compact.
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