Zoom lens system
AssigneePENTAX Corporation
InventorTakashi Enomoto
Life of this patent
Estimating the term…
Abstract
A zoom lens system includes a positive first lens group, a negative second lens group. Zooming is performed by moving the first and second lens groups in the optical axis direction thereof. The most image-side lens element of the positive first lens group includes a positive lens element having at least one aspherical surface. The zoom lens system satisfies the following conditions: 4.5<fT/f1G<5.5 (1) 3.5<fT/fLasp<5.5 (2) wherein fT designates the focal length of the zoom lens system at the long focal length extremity; f1G designates the focal length of the positive first lens group; and fLasp designates the focal length of the positive lens element having the aspherical surface in the positive first lens group.
Claims13
A zoom lens system comprising a positive first lens group, a negative second lens group, in this order from an object,
- wherein zooming is performed by moving said first and second lens groups in the optical axis direction thereof;
- wherein the most image-side lens element of said positive first lens group comprises a positive lens element having at least one aspherical surface;
- and
- wherein said zoom lens system satisfies the following conditions:
- 4.5<fT/f1G<5.5 3.5<fT/fLasp<5.5
- wherein
- fT designates the focal length of said zoom lens system at the long focal length extremity;
- f1G designates the focal length of said positive first lens group;
- and
- fLasp designates the focal length of said positive lens element having said aspherical surface in said positive first lens group.
A zoom lens system comprising a positive first lens group, a negative second lens group, in this order from an object, wherein zooming is performed by moving said first and second lens groups in the optical axis direction thereof;
- wherein said zoom lens system satisfies the following condition:
- 4.5<fT/f1G<5.5
- wherein
- fT designates the focal length of said zoom lens system at the long focal length extremity;
- and
- f1G designates the focal length of said positive first lens group.
Dependencies are inferred from the claim text.