Zoom lens system
AssigneeRicoh Imaging Company, Ltd.
InventorYoichi Nomura
Life of this patent
Estimating the term…
Abstract
A zoom lens system includes a positive first lens group, a negative second lens group, a positive third lens group and a positive fourth lens group, in that order from the object side, wherein distances between adjacent lens groups thereof change during zooming. The third lens group includes a positive first sub-lens group, a positive second sub-lens group and a negative third sub-lens group. The third sub-lens group consists of a single negative lens element. The following conditions (1) and (2) are satisfied: 6.0<f1Gp/fw<9.0 (1), and 1.3<f3Gp/f4Gp<2.0 (2), wherein fw designates the focal length of the entire zoom lens system at the short focal length extremity, f1Gp, f3Gp and f4Gp designate the focal lengths of the first, third and fourth lens groups, respectively.
Claims17
A zoom lens system comprising a positive first lens group, a negative second lens group, a positive third lens group and a positive fourth lens group, in that order from the object side, wherein distances between adjacent lens groups thereof change during zooming,
- wherein said third lens group includes a positive first sub-lens group, a positive second sub-lens group and a negative third sub-lens group, in that order from the object side,
- wherein said third sub-lens group includes a single negative lens element, and
- wherein the following conditions (1) and (2) are satisfied:
- 6.0<f1Gp/fw<9.0 (1), and
- 1.3<f3Gp/f4Gp<2.0 (2), wherein
- fw designates the focal length of the entire zoom lens system at the short focal length extremity,
- f1Gp designates the focal length of said first lens group,
- f3Gp designates the focal length of said third lens group, and
- f4Gp designates the focal length of said fourth lens group.
A zoom lens system comprising a positive first lens group, a negative second lens group, a positive third lens group and a positive fourth lens group, in that order from the object side, wherein distances between adjacent lens groups thereof change during zooming,
- wherein said third lens group includes a positive first sub-lens group, a positive second sub-lens group and a negative third sub-lens group, in that order from the object side,
- wherein said third sub-lens group includes a single negative lens element, and
- wherein the following conditions (1) and (3) are satisfied:
- 6.0<f1Gp/fw<9.0 (1), and
- 0.95<f3Ga/|f3Gc|<2.5 (3), wherein
- fw designates the focal length of the entire zoom lens system at the short focal length extremity,
- f1Gp designates the focal length of said first lens group,
- f3Ga designates the focal length of said first sub-lens group, and
- f3Gc designates the focal length of said third sub-lens group.
Dependencies are inferred from the claim text.