Optical: systems and elements – Lens – With variable magnification
Reexamination Certificate
2007-03-27
2007-03-27
Spector, David N. (Department: 2873)
Optical: systems and elements
Lens
With variable magnification
C359S680000, C359S689000
Reexamination Certificate
active
11458561
ABSTRACT:
At least one exemplary embodiment is directed to a zoom lens which includes, in order from an object side to an image side, a first lens unit, which can have a negative refractive power; a second lens unit, which can have a positive refractive power; and a third lens unit, which can have a negative refractive power. The second and third lens units can move in zooming. The first, second, and, third lens units can satisfy the following conditions:in-line-formulae description="In-line Formulae" end="lead"?1.2<|φ1/φT|<2in-line-formulae description="In-line Formulae" end="tail"?in-line-formulae description="In-line Formulae" end="lead"?0.9<φ2/φT<2.2in-line-formulae description="In-line Formulae" end="tail"?in-line-formulae description="In-line Formulae" end="lead"?0.75<φ3/φ1<1.2in-line-formulae description="In-line Formulae" end="tail"?wherein φ1, φ2, and φ3are the refractive powers of the first, second, and third lens units, respectively, and φT is the refractive power of the zoom lens at a telephoto end.
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Canon Kabushiki Kaisha
Canon USA , Inc. Intellectual Property Division
Spector David N.
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