Zoom lens

Details Zoom lens Zoom lens

2007-10-23

2007-10-23

Sugarman, Scott J. (Department: 2873)

Optical: systems and elements

Lens

With variable magnification

Reexamination Certificate

active

11002401

ABSTRACT:
In a zoom lens of this invention, a first lens group having a positive refraction power, a second lens group having a negative refraction power, a third lens group having a positive refraction power, and a fourth lens group having a positive refraction power are arranged sequentially from an object side toward an image side, and the magnification is changed from the wide angle end of the zoom lens to the telephoto end thereof, and vice versa, by varying each distance between each pair of the first to the fourth lens groups. The first lens group includes a positive lens and a negative lens. The third lens group includes at least a positive lens and a negative lens arranged sequentially from the object side toward the image side. At least the positive lens of the third lens group is a spherical lens. That lens of the third lens group which is located closest to the image side is a lens having an aspherical surface on at least one surface thereof.

REFERENCES:
patent: 4690513 (1987-09-01), Takahashi et al.
patent: 6178049 (2001-01-01), Mukaiya et al.
patent: 2002-006216 (2002-01-01), None
patent: 2002-244039 (2002-08-01), None
patent: 2003-315676 (2003-11-01), None

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