Optical: systems and elements – Lens – With variable magnification
Reexamination Certificate
2007-02-12
2008-09-16
Sugarman, Scott J (Department: 2873)
Optical: systems and elements
Lens
With variable magnification
C359S680000
Reexamination Certificate
active
07426080
ABSTRACT:
At least one exemplary embodiment is directed to a zoom lens comprising a plurality of lens units, where the plurality of lens units have at least one negative lens including a first negative lens Gn1 arranged at a position where an effective diameter is minimized among negative lenses of the zoom lens, where when the at least one negative lens is represented by an ithnegative lens Gni indicating the ithnegative lens from an expansion side toward the reduction side and Xi=θgFni−(0.6438−0.001682×νdni), the following condition is satisfied:in-line-formulae description="In-line Formulae" end="lead"?(ΣXi×fni)/(Σfni)<−0.003,in-line-formulae description="In-line Formulae" end="tail"?where the Abbe number and the partial dispersion ratio of the material of the ithnegative lens Gni are νdni and θgFni, respectively, and the focal length of the ithnegative lens Gni is fni.
REFERENCES:
patent: 6816320 (2004-11-01), Wada
patent: 7016118 (2006-03-01), Wada
patent: 7193789 (2007-03-01), Maetaki
patent: 7382550 (2008-06-01), Nishimura
patent: 2004-054021 (2004-02-01), None
patent: 2005-062225 (2005-03-01), None
Canon Kabushiki Kaisha
Canon U.S.A. Inc. IP Division
Sugarman Scott J
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