Compact zoom lens

Details Compact zoom lens Compact zoom lens

2010-10-13

2011-12-27

Greece, James (Department: 2873)

Optical: systems and elements

Lens

With variable magnification

C359S676000

Reexamination Certificate

active

08085480

ABSTRACT:
A zoom lens including a first lens group having a negative refractive power, including a negative lens and a positive lens and having at least one aspherical surface, a second lens group having a positive refractive power, a third lens group having a positive refractive power, and a fourth lens group having a positive refractive power. During, zooming from a wide angle position to a telephoto position, the first lens group is moved so that the first lens group at the telephoto position is closer to the object side than the first lens group at the wide angle position, the second lens group is moved, the third lens group is moved toward the object side from the image side, and the fourth lens group is moved so that the distance between the third lens group and the fourth lens group at the telephoto position is larger than the distance therebetween at the wide angle position, andthe zoom lens satisfies the following Equations:in-line-formulae description="In-line Formulae" end="lead"?vdG1−p>56.0in-line-formulae description="In-line Formulae" end="tail"?in-line-formulae description="In-line Formulae" end="lead"?2.1<|β3T/β3W|<5.5,in-line-formulae description="In-line Formulae" end="tail"?where vdG1−p is the Abbe's number of the positive lens of the first lens group, β3T is the magnification of the third lens group at the telephoto position and β3W is the magnification of the third lens group at the wide angle position, respectively.

REFERENCES:
patent: 2005/0243437 (2005-11-01), Hozumi et al.

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