Optical: systems and elements – Lens – With variable magnification
Reexamination Certificate
2010-02-02
2010-12-21
Lester, Evelyn A. (Department: 2873)
Optical: systems and elements
Lens
With variable magnification
C359S649000, C359S680000, C359S683000, C359S684000, C359S685000, C359S714000, C359S740000, C359S753000, C359S770000
Reexamination Certificate
active
07855840
ABSTRACT:
A projection zoom lens includes in order from an enlargement side: a first lens group with negative power; a second lens group with positive power; a third lens group with positive power; a fourth lens group with positive power; and a fifth lens group with positive power, wherein the first and fifth lens groups are fixed and the second, third, and fourth lens groups move when zooming from a wide angle side to a telescopic side, the second lens group includes only a positive lens which is convex toward the enlargement side, and assuming that the focal length at a wide angle end of a whole system including the first to fifth lens groups is F and the focal length of the second lens group is F2, the following conditional expression (1) is satisfied:in-line-formulae description="In-line Formulae" end="lead"?0.05<F/F2<0.23 (1).in-line-formulae description="In-line Formulae" end="tail"?
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Lester Evelyn A.
Oliff & Berridg,e PLC
Seiko Epson Corporation
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