Three-group zoom lens

Details Three-group zoom lens Three-group zoom lens

2007-01-16

2007-01-16

Spector, David N. (Department: 2873)

Optical: systems and elements

Lens

With variable magnification

C359S684000

Reexamination Certificate

active

11155553

ABSTRACT:
A three-group zoom lens includes five lens components and six lens elements. The first lens group from the object side has negative refractive power and both the second lens group, which includes a stop, and the third lens group from the object side have positive refractive powers. The first and second lens groups each include an aspheric surface. During zooming, the first lens group moves nearer the second lens group while the second lens group moves farther from the third lens group. The third lens group moves toward the object side when focusing from an object at infinity to a nearby object. The three lens groups have particular lens element constructions, and lens elements of the second and third lens groups satisfy certain conditions related to their focal lengths, Abbe numbers, and the focal length of the zoom lens.

REFERENCES:
patent: 6785057 (2004-08-01), Ori
patent: 6919994 (2005-07-01), Tanaka
patent: 6943960 (2005-09-01), Ori et al.
patent: 6982834 (2006-01-01), Sato
patent: 6985300 (2006-01-01), Sato
patent: 6995924 (2006-02-01), Sato
patent: 2000-284177 (2000-10-01), None
patent: 2004-93647 (2004-03-01), None

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