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:
Apr. 15, 2003
Filed:
Aug. 22, 2001
Shuji Yoneyama, Saitama, JP;
Pentax Corporation, Tokyo, JP;
Abstract
An intermediate telephoto lens system includes a first lens group and a second lens group. The first lens group includes a first lens element, a second lens element, a third lens element, an aperture stop, cemented lens elements constituted by a fourth lens element and a fifth lens element, and a sixth lens element. The second lens group includes a seventh lens element and an eighth lens element. Upon focusing, only the first lens group moves along the optical axis. The intermediate telephoto lens system satisfies the following condition: (&ngr;′ +&ngr;′ )/2>102 . . . (1); &ngr;′ : the dispersion ratio of the first lens element; &ngr;′ : the dispersion ratio of the second lens element; &ngr;′=(n −1)/(n −n ); n : the refractive index of the d-line for each lens element; n : the refractive index of the g-line for each lens element n the refractive index of the F-line for each lens element.