Zoom lens and imaging apparatus

Details Zoom lens and imaging apparatus Zoom lens and imaging apparatus

2011-08-16

2011-08-16

Spector, David N (Department: 2873)

Optical: systems and elements

Lens

With variable magnification

C359S686000, C348S240300

Reexamination Certificate

active

08000024

ABSTRACT:
A zoom lens is provided and includes: a first lens group having a positive power, a second lens group having a negative power, a stop, a third lens group having a positive power, and a fourth lens group having a positive power in order. Zooming is performed by moving at least the first lens group, the second lens group, the stop, and the third lens group along the optical axis. During zooming, the stop is moved so as to be closer to an image plane at a wide-angle end than at a telephoto end and to be closer to the second lens group at the telephoto end than at the wide-angle end. The following conditional expressions (1) and (2) are satisfied. For the conditional expressions (1) and (2), fw is a focal length at the wide-angle end of the entire system, ft is a focal length at the telephoto end of the entire system, f1is a composite focal length of the first lens group, and X1is a displacement of the first lens group during zooming from the wide-angle end to the telephoto end.in-line-formulae description="In-line Formulae" end="lead"?4.0<f1/fw<7.0  (1)in-line-formulae description="In-line Formulae" end="tail"?in-line-formulae description="In-line Formulae" end="lead"?0.2<X1/ft<0.3  (2)in-line-formulae description="In-line Formulae" end="tail"?

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patent: 2005/0168832 (2005-08-01), Hamano
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patent: 3392881 (2003-03-01), None
patent: 2005-215385 (2005-08-01), None
patent: 3706783 (2005-10-01), None
patent: 2006-235062 (2006-09-01), None

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