Zoom lens system
AssigneeAsahi Kogaku Kogyo Kabushiki Kaisha
InventorsTakashi Enomoto, Takayuki Ito, Shuji Yoneyama
Life of this patent
Estimating the term…
Abstract
A zoom lens system having a positive first lens group and a negative second lens group in this order from the object side, wherein zooming is performed by varying the distance between the first and the second lens groups. The zoom lens system satisfies the following conditions (1) and (2): 1.4<fw/f1G<1.7 (1) 0.85<Σd1G/fw<1.1 (2) wherein: fw designates the focal length of the zoom lens system at the short focal length extremity; and f1G designates the focal length of the positive first lens group; and Σd1G designates the thickness of the positive first lens group.
Claims6
A zoom lens comprising a positive first lens group and a negative second lens group positioned in this order from the object side, wherein zooming is performed by varying the distance between said positive first lens group and said negative second lens group;
- said zoom lens system satisfying the following relationships:
- 1.4<fw/f1G<1.7
- 0.85<Σd1G/fw≦0.99
- wherein:
- fw designates the focal length of said zoom lens system at the short focal length extremity;
- f1G designates the focal length of said positive first lens group;
- and
- Σd1G designates the thickness of said positive first lens group.
A zoom lens system forming an image on an image plane with a diagonal of more than 60 mm, said zoom lens system comprising a positive first lens group and a negative second lens group positioned in this order from the object side, wherein zooming is performed by varying the distance between said positive first lens group and said negative second lens group said zoom lens system satisfying the following relationships:
- 1.4<fw/f1G<1.7
- 0.85<Σd1G/fw<1.1
- wherein:
- fw designates the focal length of said zoom lens system at the short focal length extremity;
- f1G designates the focal length of said positive first lens group;
- and
- Σd1G designates the thickness of said positive first lens group.
Dependencies are inferred from the claim text.