Invention Grant
- Patent Title: Wide-angle zoom lens
- Patent Title (中): 广角变焦镜头
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Application No.: US12662355Application Date: 2010-04-13
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Publication No.: US08169718B2Publication Date: 2012-05-01
- Inventor: Dayong Li , Hiroshi Yamamoto , Hiroki Harada
- Applicant: Dayong Li , Hiroshi Yamamoto , Hiroki Harada
- Applicant Address: JP Saitama JP Tokyo
- Assignee: Tamron Co., Ltd.,Nikon Corporation
- Current Assignee: Tamron Co., Ltd.,Nikon Corporation
- Current Assignee Address: JP Saitama JP Tokyo
- Agency: Jacobson Holman PLLC
- Priority: JP2009-097397 20090413; JP2009-097398 20090413; JP2009-097399 20090413; JP2009-097400 20090413
- Main IPC: G02B9/34
- IPC: G02B9/34

Abstract:
The present invention is directed to wide-angle zoom lenses dedicated to single-lens reflex digital cameras, which attains zoom ratio greater than 2. Such a wide-angle zoom lens has four groups of lens pieces, namely comprising the leading or foremost 1st lens group of negative refractivity closest to an objective field, the succeeding 2nd lens group of positive refractivity, the third lens group of negative refractivity, and the trailing 4th lens group of positive refractivity arranged in this order to move each lens group to vary optical power; and the 1st lens group includes a front subset of the lens pieces of negative refractive power and a rear subset of negative refractive power. The front-end lens piece in the 1st lens group is shaped in negative meniscus lens that has its concave surface faced toward an imaging plane and has the opposite surfaces shaped aspherical. The front and rear subsets of the 1st lens group meet requirements of a focal length as expressed in the following formula: 3.5≦|f1b/f1a|≦6.0 where f1a is a focal length of the front subset of the lens pieces in the 1st lens group and f1b is the focal length of the rear subset in the 1st lens group.
Public/Granted literature
- US20100259834A1 Wide-angle zoom lens Public/Granted day:2010-10-14
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