Zoom lens

Details Zoom lens Zoom lens

1995-06-13

1997-05-06

Epps, Georgia Y.

Optical: systems and elements

Lens

With variable magnification

359742, G02B 1514, G02B 308

Patent

active

056276818

ABSTRACT:
An improved zoom lens for use in projective image forming systems is disclosed. It comprises, in the order from the object side to the image side, a first lens group with a negative refractive power, a second lens group with a positive refractive power, a third lens group with a negative refractive power, and a fourth lens group with a positive refractive power. The lens groups are disposed such that, during the zooming operation from the wide-angle mode to the telephoto mode, the first, second, and third lens groups are simultaneously moving toward the object side and the fourth lens group stays stationary, and that the first and third zoom lens groups are provided such that the following condition is satisfied: 1.6<k1/k3<4, where k1 is an absolute value of the refractive power of the first lens group and k3 is an absolute value of the refractive power of the third lens group. In a preferred embodiment, the fourth lens group comprises a Fresnel lens.

REFERENCES:
patent: 3481664 (1969-12-01), Takano
patent: 4687302 (1987-08-01), Ikemori et al.
patent: 5276553 (1994-01-01), Tatsuno
patent: 5285317 (1994-02-01), Uzawa

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