Optical: systems and elements – Lens – With variable magnification
Reexamination Certificate
2006-09-05
2006-09-05
Ben, Loha (Department: 2873)
Optical: systems and elements
Lens
With variable magnification
C359S682000
Reexamination Certificate
active
07102830
ABSTRACT:
The invention has for its object to use a zoom system that comprises a reduced number of lens elements, is compact and simplified, and has high image-formation capability, thereby achieving thorough size reductions in video cameras or digital cameras. A zoom lens for use on an electronic imaging system comprises a negative first lens group G1, an aperture stop S, a positive second lens group G2and a positive third lens group G3. Upon zooming from the wide-angle end to the telephoto end of the zoom lens, the second lens group G2moves only toward the object side of the zoom lens and the third lens group G3moves in a locus different from that of the second lens group G2. The second lens group G2is made up of a positive first lens element having an aspheric surface on its object side, a negative second lens element, a positive third lens element and a negative fourth lens element. The first and second lens elements are cemented together, and the third lens group G3moves independently for focusing. The second lens group G2satisfies condition (1) with respect to the Abbe numbers of the third and fourth lens elements, condition (2) with respect to the shape of the third lens element, and condition (3) with respect to the composite focal length of the third and fourth lens elements.
REFERENCES:
patent: 6498688 (2002-12-01), Shibayama
patent: 6671103 (2003-12-01), Itoh
Ben Loha
Choi William
Kenyon & Kenyon LLP
Olympus Corporation
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