Rear-focus type zoom lens suppressing fluctuation of aberration

Details Rear-focus type zoom lens suppressing fluctuation of aberration Rear-focus type zoom lens suppressing fluctuation of aberration

1991-07-15

1992-08-11

Sugarman, Scott J.

Optical: systems and elements

Lens

With variable magnification

359708, 359713, G02B 1514, G02B 1318

Patent

active

051384922

ABSTRACT:
A zoom lens of the rear focus type of the invention comprises, from an object side, a first lens unit of positive refractive power, a second lens unit of negative refractive power, a third lens unit of positive refractive power and a fourth lens unit of positive refractive power. The second lens unit is moved toward an image side to effect zooming from a wide-angle end to a telephoto end, while an image shift resulting from the zooming is compensated for by moving the fourth lens unit, and focusing is performed by moving the fourth lens unit. Letting the focal length of the i-th lens unit be denoted by F.sub.i, the local length of the entire lens system in the telephoto end by F.sub.T, the F-number at full open aperture in the telephoto end by F.sub.NOT and the semi-angle of view in the telephoto end by T, at least one of the following conditions (1), (2) and (3) is satisfied: ##EQU1##

REFERENCES:
patent: 4842385 (1989-06-01), Tanaka
patent: 5009492 (1991-04-01), Hamano

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