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. 23, 1989
Filed:
Feb. 05, 1988
Koichi Wakamiya, Tokyo, JP;
Nikon Corporation, Tokyo, JP;
Abstract
A viewfinder system capable of changing over the magnification includes an objective lens unit having at least two negative lens elements replaceable with each other for magnification change-over, and an eyepiece unit having a positive refractive power and constituting an inverted Galilean telescope type viewfinder with the objective lens unit. When the radius of curvature of that surface of one negative lens element for low magnification which is adjacent to the object side is rw.sub.1 and the radius of curvature of that surface of said one negative lens element which is adjacent to the eyepiece side is rw.sub.2 and the radius of curvature of that surface of the other negative lens element for high magnification which is adjacent to the object side is rT1 and the radius of curvature of that surface of said other negative lens element which is adjacent to the eyepiece side is rT2 and Q.sub.W and Q.sub.T are defined as