Optical: systems and elements – Lens – With variable magnification
Reexamination Certificate
2006-01-31
2006-01-31
Spector, David N. (Department: 2873)
Optical: systems and elements
Lens
With variable magnification
C359S680000, C348S240300
Reexamination Certificate
active
06992835
ABSTRACT:
A zoom lens has an optical axis and includes: a negative first lens group capable of being moved for zooming and disposed nearest to the front end; a positive second lens group capable of being moved for zooming, and disposed behind the first lens group; and a positive third lens group disposed behind the second lens group. The zoom lens meets conditions expressed by inequalities:in-line-formulae description="In-line Formulae" end="lead"?0.02<D12/fw<0.13 (1)in-line-formulae description="In-line Formulae" end="tail"?in-line-formulae description="In-line Formulae" end="lead"?0.5<D2G/fw<0.95 (2)in-line-formulae description="In-line Formulae" end="tail"?in-line-formulae description="In-line Formulae" end="lead"?5<TLW/fw<8 (3)in-line-formulae description="In-line Formulae" end="tail"?where D12 is a minimum distance on the optical axis between a back surface of the first lens group and a front surface of the second lens group, D2G is a distance between front and back surfaces of the second lens group, TLW is optical length of the zoom lens as set in the shortest focal length, and fw is the shortest focal length.
REFERENCES:
patent: 5900987 (1999-05-01), Kreitzer
patent: 2002/0191306 (2002-12-01), Toyama
patent: 1 220 002 (2002-07-01), None
PatentAbstracts of Japan, JP 2002-350726, Dec. 4, 2002.
Iwasawa Yoshito
Sueyoshi Masafumi
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Spector David N.
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