Optical: systems and elements – Lens – With variable magnification
Patent
1993-10-12
1995-07-18
Epps, Georgia Y.
Optical: systems and elements
Lens
With variable magnification
359716, 359715, G02B 1514, G02B 302
Patent
active
054347114
ABSTRACT:
The improved zoom lens system comprises, in order from the object side, a positive first lens group, a positive second lens group and a negative third lens group, the second lens group consisting of a single positive lens group that has aspheric surfaces on both surfaces closest to the object and closest to the image, and all of the first, second and third lens groups are moved towards the object during a zoom from the wide-angle end to the narrow-angle end, the lens system further satisfying specific conditions.
This zoom lens system is capable of exhibiting a zoom ratio of at least 2.5 using 4 or 5 lens elements and has an F number of about 1:4-8 to make itself practical for use with still cameras.
REFERENCES:
patent: 4822152 (1989-04-01), Yamanashi
patent: 5087988 (1992-02-01), Nakayama
patent: 5166828 (1992-11-01), Ogata
patent: 5327290 (1994-07-01), Fukushima et al.
Takayuki Ito
Tetsuya Abe
Asahi Kogaku Kogyo Kabushiki Kaisha
Epps Georgia Y.
Lester Evelyn A.
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