| 摘要 |
Described herein is a variable magnification duplicator lens system which is provided with, on the subject side of a stop, a front lens group including a 1st lens element consisting of a meniscus lens of positive power and facing the convex side thereof toward the subject, a 2nd lens element consisting of a meniscus lens of negative power facing the convex side thereof toward the subject, a 3rd lens element with positive power, and a 4th lens element with negative power, and on the image-forming side of the stop, a rear lens group including 5th, 6th, 7th, and 8th lens elements arranged symmetrically with the 1st to 4th lens elements of the front lens group, respectively. Of these lens elements, the 3rd to 6th lens elements and at least one of the 1st and 8th lens elements are movable. When shifting the whole lens system in the direction of the optical axis to vary the duplication scale, a reduced scale position is assumed by a lens position adjustment shifting the 5th and 6th lens elements into positions closer to the stop while at least shifting the 8th lens element toward the 7th lens element or shifting the 1st lens element away from the 2nd lens element, and an enlarged scale position is assumed by a lens position adjustment shifting the 3rd and 4th lens elements closer to the stop while at least shifting the 1st lens element toward the 2nd lens element or shifting the 8th lens elements away from the 7th lens element.
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