Zoom lens system
AssigneeHoya Corporation
InventorMasakazu Saori
Life of this patent
Estimating the term…
Abstract
A zoom lens system includes a positive first lens group, a negative second lens group, and a rear lens group which is provided on the image side of the negative second lens group, and has a combined positive refractive power, in this order from the object; and the zoom lens system satisfies the following conditions: 5.0<f1/fw<6.5 (1) 0.4<fRt/ft<0.55 (2) wherein f1 designates a focal length of the positive first lens group; fw designates a focal length of the entire the zoom lens system at the short focal length extremity; fRt designates a combined focal length of the positive rear lens group at the long focal length extremity; and ft designates a focal length of the entire zoom lens system at the long focal length extremity.
Claims6
A zoom lens system comprises a positive first lens group, a negative second lens group, and a rear lens group that is provided on the image side of said negative second lens group, and that has a combined positive refractive power, in this order from an object,
- wherein said zoom lens system satisfies the following conditions:
- 5.0<f1/fw<6.5
- 0.4<fRt/ft<0.55
- wherein
- f1 designates a focal length of said positive first lens group;
- fw designates a focal length of the entire zoom lens system at the short focal length extremity;
- fRt designates a combined focal length of the positive rear lens group at the long focal length extremity;
- and
- ft designates a focal length of the entire zoom lens system at the long focal length extremity,
- wherein said positive rear lens group comprises a positive third lens group, a negative fourth lens group, and a positive fifth lens group, in this order from the object.
Dependencies are inferred from the claim text.