The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 12, 1999
Filed:
Aug. 18, 1997
Kazuo Yoshikawa, Omiya, JP;
Fuji Photo Optical Co., Ltd., Omiya, JP;
Abstract
A zoom lens having four lens groups, the lens groups having refractive power, in order from the object side, of: fixed positive, variable negative, variable positive or negative, and fixed positive. The first lens group from the object side is composed of three lens subgroups, the middle subgroup of which is moved to perform focusing. The second lens group is moved to vary the amount of zoom, and the third lens group moves when the amount of zoom is varied in order to correct for movement of the image plane resulting when the second lens group is moved. Thus, the optical performance of the zoom lens is favorably maintained over the entire image plane. Further, by satisfying certain conditional equations a system that is compact and can focus objects at very near distances is obtained.