Optical: systems and elements – Lens – With variable magnification
Patent
1997-09-02
1999-10-19
Epps, Georgia
Optical: systems and elements
Lens
With variable magnification
359681, 359689, 359750, 359784, G02B 1514, G02B 1304, G02B 912
Patent
active
059698780
ABSTRACT:
A zoom lens system for use in a camera having a color filter and a CCD achieves a magnification ratio of about 2.9 or greater and a back focus of about 9.2 or greater. The zoom lens system includes in order from an object side of the lens system, a first lens group having a negative refracting power, a second lens group spaced from the first lens group and having a positive refracting power and a third lens group spaced from the second lens group and having a positive refracting power. One or both of the fifth and an eighth lens surface has an aspherical surface, the fifth and eighth lens surfaces being counted from the object side. The second lens group includes five lenses with an extra lens being located at a far end of the second lens group relative to the object side. Each of the first, second and third lens groups is movable from a first position when the lens system is in a wide position to a second position when the lens system is in a tele position.
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Epps Georgia
Lester Evelyn A.
Ricoh & Company, Ltd.
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