US Patent 7230772 Wide-angle zoom lens system
Patent 7230772 was granted and assigned to Pentax on June, 2007 by the United States Patent and Trademark Office.
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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:1.1<|f1|/fw<2.0(f1<0) (1)2.0<f4/fw<3.5 (2)2.5<fBw/fw<3.5 (3)
US Patent 07230772 Wide-angle zoom lens system US Patent 7230772 Wide-angle zoom lens system
US Patent 07230772 Wide-angle zoom lens system
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