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:
Jun. 20, 1989
Filed:
Oct. 30, 1987
Keiji Moriyama, Yokohama, JP;
Nikon Corporation, Tokyo, JP;
Abstract
A telephoto zoom lens comprising, in succession from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power, the lens groups being moved independently of each other during zooming. The telephoto zoom lens meets certain conditions, including a condition that prescribes the amount of change in spacing between the first and second lens groups by zooming, so that the spacing increases at the telephoto end. The telephoto ratio is large, and the lens is relatively compact at the wide angle end. The burden borne by each lens group regarding correction of spherical aberration is reduced, and correction of spherical aberration is relatively easy, so that the degree of freedom in lens design is enhanced.