Cushman, Darby & Cushman
Varifocal lens system
 A varifocal lens system equipped with an auxiliary lens group comprising a master lens system consisting of a front lens group having positive refractive power and a rear lens group having negative refractive power, and an auxiliary lens group arranged in such a manner that it can be freely inserted and removed, for varying focal length, between said front and rear lens groups. Said varifocal lens system is equipped with a simple mechanism capable of varying focal length of said lens system in a very short time. 
Olympus Optical Co., Ltd.
G G
G02B G02B
inventional inventional
Toru Hiroshi Masaki
Fujii Takase Imaizumi