Optical: systems and elements – Lens – With variable magnification
Patent
1996-02-16
1998-06-16
Epps, Georgia Y.
Optical: systems and elements
Lens
With variable magnification
359708, G02B 1514, G02B 302
Patent
active
057680299
ABSTRACT:
The invention relates to a positive lens group preceding type of compact zoom lens system for use on still cameras, in which the focal distance at the wide-angle end is shorter than the diagonal length of an image pickup surface, the angle of field is at least 64.degree. at the wide-angle end and the zoom ratio is at least 3, and which comprises a first positive lens group G1, a second negative lens group G2, a third positive lens group G3 and a fourth positive lens group G4 so that the first, third and fourth lens groups G1, G3 and G4 are moved toward the object side for zooming from the wide-angle end to the telephoto end. The second lens group G2 comprises three lenses, the fourth lens group G4 comprises a positive lens component and a negative lens component, and the third and fourth lens groups G3 and G4 have at least two aspheric surfaces, with conditional inequality 0.1<d.sub.4 /f.sub.W <0.5 being satisfied, where d.sub.4 is the air separation between the positive and negative lens components of said fourth lens group and f.sub.W is the composite focal distance of the overall system at the wide-angle end.
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Epps Georgia Y.
Olympus Optical Co,. Ltd.
Schwartz Jordan M.
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