Three-group zoom lens and imaging device

Details Three-group zoom lens and imaging device Three-group zoom lens and imaging device

2008-01-16

2009-02-17

Choi, William C (Department: 2873)

Optical: systems and elements

Lens

With variable magnification

C359S683000

Reexamination Certificate

active

07492527

ABSTRACT:
In a three-group zoom lens having negative power, positive power, and positive power in order from an object side, a first lens group is built from a first negative lens and a second positive biconvex lens which is formed from a plastic material and which has at least one aspherical surface; a second lens group G2is built from a positive, a negative cemented lens and a fifth lens L5assuming a meniscus shape; and a third lens group is built from a sixth lens L6which is a positive single lens. The zoom lens fulfills conditional expressions provided below:in-line-formulae description="In-line Formulae" end="lead"?3.2<fg2/fw  (1)in-line-formulae description="In-line Formulae" end="tail"?in-line-formulae description="In-line Formulae" end="lead"?26<ν1−ν2<30  (2)in-line-formulae description="In-line Formulae" end="tail"?in-line-formulae description="In-line Formulae" end="lead"?D1/fw<0.75  (3)in-line-formulae description="In-line Formulae" end="tail"?(fg2: a focal length of the second lens, fw: a focal length of an entire system achieved at a wide-angle end, ν1: Abbe number of the first lens, ν2: Abbe number of the second lens, and D1: Axial distance from a lens surface most closely positioned to the object side to a lens surface most closely positioned to an image side in the first lens group).

REFERENCES:
patent: 5585970 (1996-12-01), Shibayama
patent: 2000-267009 (2000-09-01), None
patent: 2005-285064 (2005-10-01), None
patent: 2005-321744 (2005-11-01), None
patent: 2007-193140 (2007-08-01), None

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