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:
Aug. 24, 2004
Filed:
Aug. 19, 2002
Shuji Yoneyama, Saitama, JP;
PENTAX Corporation, Tokyo, JP;
Abstract
A viewing optical system includes an objective optical system and an eyepiece optical system. The objective optical system includes a positive first meniscus lens element having the convex surface facing toward the object, a positive second meniscus lens element having the convex surface facing toward the object, a negative third lens unit constituted by two negative lens elements, and a positive fourth lens element. The fourth lens constitutes an image-blur correcting optical system movable in a direction perpendicular to the optical axis. The viewing optical system satisfies the following conditions: 0.5<|tan 1°/(&phgr; −&phgr; )|<5 (mm) . . . (1) 0.5<SF <1.0 . . . (2) wherein &phgr; designates the combined power from the positive first meniscus lens element to the positive fourth lens element; &phgr; designates the combined power from the positive first meniscus lens element to the negative third lens unit; and SF designates the shape factor of the positive fourth lens element defined as SF =(r +r )/(r −r ); r designates the radius of curvature of the object-side surface of the positive fourth lens element; and r2 designates the radius of curvature of the image-side surface of the positive fourth lens element.