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:
May. 04, 1999
Filed:
Oct. 06, 1997
Koichi Ohshita, Tokyo, JP;
Nikon Corporation, Tokyo, JP;
Abstract
A viewfinder having a high magnification ratio permits satisfactory correction of aberration in spite of its compact and simple structure. An objective lens group of the viewfinder includes a first lens unit having negative refractive power, a second lens unit having positive refractive power, and a third lens unit having negative refractive power and varies magnification by moving at least the second lens unit. Moreover, the first lens unit includes at least one negative lens, the second lens unit includes at least two positive lenses, and the third lens unit includes at least one negative lens. Furthermore, the positive lens is formed so that an object-side surface is aspherical and a predetermined condition is satisfied.