Optical: systems and elements – Lens – With variable magnification
Reexamination Certificate
2006-02-07
2006-02-07
Spector, David N. (Department: 2873)
Optical: systems and elements
Lens
With variable magnification
C359S689000, C359S685000, C359S680000
Reexamination Certificate
active
06995921
ABSTRACT:
A zoom lens apparatus includes a first optical lens group having a negative focal length, a second optical lens group having a positive focal length, and a third optical lens group having a positive focal length, arranged in this order from a subject. The lens groups move such that a distance between the first and second optical lens groups is decreased and a distance between the second and third optical lens groups is increased at a scaling change to a long focal length edge. The second optical lens group includes two positive lenses, a negative meniscus lens, and a positive meniscus lens. The zoom lens system satisfies an inequality condition 0.15<(N22−N23)<0.40, in which N22 is a refractive index of the negative meniscus lens and N23 is a refractive index of the positive meniscus lens conjoined with the negative meniscus lens.
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Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Ricoh & Company, Ltd.
Spector David N.
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