High zoom-ratio zoom lens system
AssigneeHoya Corporation
InventorMasaru Eguchi
Life of this patent
Estimating the term…
Abstract
A high zoom-ratio 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. Upon zooming from the short to long focal length extremities, at least the first through third lens groups are moved along the optical axis direction, wherein an amount of movement of the first lens group is greater than that of the third lens group. The following conditions (1), (2) and (3) are satisfied: 0.9<FT/F1<2 (1), 3<F1/FW<7 (2), and −8<F1/F2<−5 (3), wherein FT and FW designate the entire focal length of the zoom lens system at the long and short focal length extremities, respectively; and F1 and F2 designate the focal length of the first and second lens groups, respectively.
Claims11
A high zoom-ratio 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 upon zooming from the short focal length extremity to the long focal length extremity, at least the first through third lens groups are moved along the optical axis direction, wherein an amount of movement of said first lens group along the optical axis direction is greater than that of said third lens group, and
- wherein the following conditions (1), (2) and (3) are satisfied:
- 0.9<FT/F1<2 (1),
- 3<F1/FW<7 (2), and
- −8<F1/F2<−5 (3), wherein
- FT designates the entire focal length of the zoom lens system at the long focal length extremity,
- F1 designates the focal length of the first lens group,
- FW designates the entire focal length of the zoom lens system at the short focal length extremity, and
- F2 designates the focal length of the second lens group.
Dependencies are inferred from the claim text.