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:
Nov. 24, 2020
Filed:
Nov. 09, 2018
Canon Kabushiki Kaisha, Tokyo, JP;
Junya Ichimura, Utsunomiya, JP;
CANON KABUSHIKI KAISHA, Tokyo, JP;
Abstract
An optical system according to the present invention is an optical system comprises a first lens unit having positive refractive power, a second lens unit having positive refractive power, and a third lens unit having negative refractive power, arranged in order from an object side to an image side. During focusing from infinity to a closest distance, the second lens unit moves to the object side, whereby a distance between adjoining lens units is changed. The second lens unit comprises an aperture stop. The following conditional expression is satisfied:1.0<3/<3.0,where D3 is a length of the third lens unit on an optical axis, and BF is a back focus distance.