Optical: systems and elements – Lens – With variable magnification
Patent
1997-07-28
1999-03-23
Epps, Georgia
Optical: systems and elements
Lens
With variable magnification
359679, 359716, 359740, 359791, G02B 1514, G02B 302, G02B 900, G02B 912
Patent
active
058868291
ABSTRACT:
The zoom lens according to the present invention comprises three lens units. More specifically, there is a front lens unit of positive refractive power consisting of a positive lens element and a negative lens element, a middle lens unit of positive refractive power, and a rear lens unit of negative refractive power. During zooming from a wide-angle to a telephoto position, the front lens unit and the rear lens unit simultaneously movable towards an object side during zooming from a wide angle to a telephoto position. The middle lens unit moves towards the object side at a relatively slower speed than that at which the front and the rear lens units are moved. The lens elements have sufficient optical powers, spacings and radii of curvature to provide for a large zoom ratio ZR and to maintain an overall compactness so that L.sub.v /f.sub.t <0.9 and ZR=f.sub.t /f.sub.w >2.3, where L.sub.v is the distance from the front vertex of the lens system to the film plane in the telephoto position, f.sub.t is the focal length of the lens system in the telephoto position, and f.sub.w is the focal length of the zoom lens system in the wide-angle position. At least one lens element comprising the middle or the rear lens unit has a V-number greater than 70. According to a preferred embodiment, this V-number is greater than 80. Also, according to a preferred embodiment the front and the rear lens units are integral so as to be simultaneously movable for zooming at the same speed and direction.
REFERENCES:
patent: 4726668 (1988-02-01), Nakayama et al.
patent: 4854682 (1989-08-01), Yamanashi
patent: 5069536 (1991-12-01), Ogata
patent: 5216547 (1993-06-01), Ogata
patent: 5260833 (1993-11-01), Ito et al.
patent: 5325235 (1994-06-01), Takashima et al.
patent: 5353159 (1994-10-01), Morooka
patent: 5353160 (1994-10-01), Ogata
patent: 5379154 (1995-01-01), Shibayama et al.
patent: 5434711 (1995-07-01), Tetsuya et al.
patent: 5572365 (1996-11-01), Ito
patent: 5715096 (1998-02-01), Meyers
patent: 5726810 (1998-03-01), Meyers
Eastman Kodak Company
Epps Georgia
Lester Evelyn A.
Short Svetlana Z.
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