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:
Sep. 22, 2009
Filed:
Jan. 23, 2009
Takeshi Nishimura, Utsunomiya, JP;
Takeshi Nishimura, Utsunomiya, JP;
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
A zoom lens includes first to fourth lens units which respectively have negative, positive, negative, and positive refractive powers in order from the object side to the image side. Distances between the first and second lens units, the second and third lens units, and the third and fourth lens units at the telephoto end are respectively smaller, larger, and smaller than those at the wide-angle end. An Abbe number ν1n and a partial dispersion ratio θ1n of a material of at least one negative lens included in the first lens unit, an Abbe number ν1p, a partial dispersion ratio θ1p, and a refractive index N1p, respectively, of a material of at least one positive lens included in the first lens unit, a focal length f1 of the first lens unit, and a focal length fw of the entire system at the wide-angle end are adequately set.