| 摘要 |
An aberrational deterioration preventing zoom lens comprising a lens group axially movable for zooming, another lens group axially movable for zooming which has a plurality of lens units, an aperture diaphragm on the object side of the rear lens unit having an opening the size of which is variable to determine the F-number of the entire system, and an optical stop lying on the image side of the rear lens unit which positions an intersection P at which a marginal ray of the on-axial pencil corresponding to the full aperture and an upper marginal ray of the off-axial light pencil going to the margin Q of an image plane intersect each other, to restrict the on-axial light flux.
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