Zoom lens system capable of close-up photography

Claim 1

A zoom lens capable of close-up photography comprising a lens system including positive focusing lenses, negative variable power lenses, a negative correcting lens and a positive fixed lens or including positive focusing lenses, negative variable power lenses, a positive correcting lens, and a negative fixed lens, characterized by a main lens-barrel having a straight groove parallel to an optical axis thereof, a cam cylinder mounted in said main lens-barrel and having cam grooves formed therein, said variable power lenses and said correcting lens having respective lens-barrels mounted in said cam clyinder in spaced relation, pins extending from said lens-barrels through said cam grooves into said straight groove in said main lens-barrel, means for moving said cam cylinder between a rearward position for ordinary photography and a forward position for close-up photography, means for moving said variable power lenses and said correcting lens together along the optical axis without changing the space between said two lens groups, and means for rotating the cam cylinder to move said variable power lenses and said correcting lens toward and away from each other along the optical axis due to engagement of said pins with said cam and straight grooves, whereby adjustment of the focus for close-up photography can be made in the same way as in a zooming operation when the cam cylinder is in said forward position.