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:
Dec. 08, 2009
Filed:
Aug. 06, 2008
Tsuyoshi Wakazono, Utsunomiya, JP;
Tomoyuki Nakamura, Utsunomiya, JP;
Tsuyoshi Wakazono, Utsunomiya, JP;
Tomoyuki Nakamura, Utsunomiya, JP;
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
A zoom lens has, in order from the object side to the image side, a first lens unit that does not move during zooming and has positive refractive power, a second lens unit that performs zooming and has negative refractive power, a third lens unit that corrects image plane variation caused by zooming and has negative refractive power, and a fourth lens unit that does not move during zooming and has positive refractive power. The first lens unit has, in order from the object side to the image side, a first lens subunit that does not move during focusing and has negative refractive power, a second lens subunit that is configured to move along the optical axis during focusing and has positive refractive power, a third lens subunit that does not move during focusing and has positive refractive power. The second lens subunit has at least one aspherical lens surface AS12.