Variable magnification lens system with constant object-image distance

摘要

The present invention is a variable magnification lens system with a constant object-image distance. The lens system comprises an aperture stop, two fixed lens units constructed symmetrically with each other and two movable lens units constructed symmetrically with each other and located between the two fixed lens units, wherein the two lens units are positioned symmetrically with each other with respect to the aperture stop at the time of equal magnification, while the two lens units are positioned asymmetrically with each other with respect to the aperture stop during other magnification ratios.