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US 7,443,603 B2Granted
Wide-angle zoom lens system
AssigneeHoya Corporation
InventorMasakazu Saori
Life of this patent
Estimating the term…
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AssigneeHoya Corporation
InventorMasakazu Saori
Estimating the term…
A wide-angle zoom lens system includes a negative first lens group, a positive second lens group, a negative third lens group and a positive fourth lens group, in this order from the object. Upon zooming from the short focal length extremity to the long focal length extremity, a distance between the negative first lens group and the positive second lens group decreases, a distance between the positive second lens group and the negative third lens group increases, and a distance between the negative third lens group and the positive fourth lens group decreases. The wide-angle zoom lens system satisfies the following conditions: 0.9<f2/ft<1.2 (1) 2.9<f4/fw<3.4 (2) wherein f2: the focal length of the positive second lens group; f4: the focal length of the positive fourth lens group; ft: the focal length of the entire wide-angle zoom lens system at the long focal length extremity; and fw: the focal length of the entire wide-angle zoom lens system at the short focal length extremity.
A wide-angle zoom lens system comprises a negative first lens group, a positive second lens group, a negative third lens group and a positive fourth lens group, in this order from an object;
Dependencies are inferred from the claim text.