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:
Oct. 06, 2015
Filed:
Mar. 18, 2014
Canon Kabushiki Kaisha, Tokyo, JP;
Takashi Okada, Saitama, JP;
CANON KABUSHIKI KAISHA, Tokyo, JP;
Abstract
A zoom lens includes, in order from an object side to an image side, first to fourth lens units having positive, negative, positive and positive refractive powers, respectively. The intervals between adjacent lens units vary during zooming. The first lens is disposed nearer to an object at the telephoto end than at the wide angle end. Each of the first lens unit to the fourth lens unit includes at least one negative lens. The lens total length Lt, the focal length ft, the mean value N2an of the refractive indices of materials of negative lenses of the second lens unit, the mean value NAan of the refractive indices of materials of the negative lenses included in the entire system, and the mean value NAap of the refractive indices of materials of the positive lenses included in the entire system are appropriately configured.