Optical: systems and elements – Lens – With variable magnification
Patent
1996-06-18
1998-05-26
Sugarman, Scott J.
Optical: systems and elements
Lens
With variable magnification
359688, G02B 1514
Patent
active
057575541
ABSTRACT:
A zoom lens comprises, in order from an object side to an image side, a first lens unit of positive refractive power which is stationary during zooming, a second lens unit of negative refractive power which is axially movable during zooming, a third lens unit which is axially movable during zooming, and a fourth lens unit of positive refractive power which is stationary during zooming, wherein the first lens unit comprises a front lens sub-unit including at least one positive lens and having a negative refractive power as a whole, an intermediate lens sub-unit including at least one positive lens and a cemented lens and having a positive refractive power as a whole, and a rear lens sub-unit including a cemented lens and having a positive refractive power as a whole, and wherein the intermediate lens sub-unit is moved toward the image side to effect focusing from an infinitely distant object to an object at a minimum object distance.
REFERENCES:
patent: 3563636 (1971-02-01), Macher
patent: 4099845 (1978-07-01), Takesi et al.
patent: 4110006 (1978-08-01), Ikemori
patent: 4752121 (1988-06-01), Kitagishi
patent: 4765722 (1988-08-01), Aono
patent: 5097360 (1992-03-01), Fukami et al.
patent: 5136431 (1992-08-01), Terasawa et al.
patent: 5191475 (1993-03-01), Terasawa et al.
Patent Abstracts of Japan, vol. 18, No. 627 (P-1834), Nov. 29, 1994 (JP 6-242378, Sep. 2, 1994).
Patent Abstracts of Japan, vol. 4, No. 95 (P-18), Jul. 9, 1980 (JP 55-57815, Apr. 30, 1980).
Canon Kabushiki Kaisha
Sugarman Scott J.
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