Optical: systems and elements – Lens – With variable magnification
Patent
1989-12-12
1991-08-27
Arnold, Bruce Y.
Optical: systems and elements
Lens
With variable magnification
359676, G02B 1514
Patent
active
050429272
ABSTRACT:
A zoom lens is disclosed comprising, from front to rear, a first lens group of positive power, a second lens group of negative power, a third lens group of positive power, a fourth lens group of positive power, and a fifth lens group of negative power, at least a predetermined plurality of lens groups of the first to fifth lens groups being made to move in such a manner that when zooming from the wide-angle end to the telephoto end, the first lens group is moved forward, while simultaneously monotonously increasing the air separation between the first and second lens groups and monotonously decreasing the air separations between the second and third lens groups and between the fourth and fifth lens groups, and the zoom lens satisfying the following conditions: 0.05 fT/fW<.DELTA.e34/DW<0.15 fT/fW 0.05<f5/f12W<0.6 where fW and fT are the shortest and longest focal lengths of the entire lens system, f5 is the focal length of the fifth lens group, f12W is the overall focal length of the first and second lens groups at the wide-angle end, .DELTA.e34 is a changed amount of the principle point interval between the third and fourth lens groups at the telephoto end from that at the wide-angle end and DW is the length of the entire lens system from the first lens surface to the last lens surface.
REFERENCES:
patent: 4861145 (1989-08-01), Kikuchi
patent: 4871243 (1989-10-01), Ogawa et al.
Endo Hiroshi
Ogawa Hideki
Arnold Bruce Y.
Canon Kabushiki Kaisha
Gass Rebecca D.
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