Telephoto zoom lens system

Details Telephoto zoom lens system Telephoto zoom lens system

2007-08-15

2009-02-10

Lester, Evelyn A. (Department: 2873)

Optical: systems and elements

Lens

With variable magnification

C359S684000, C359S715000, C359S740000, C359S774000

Reexamination Certificate

active

07489452

ABSTRACT:
A telephoto zoom lens system includes a positive first lens group, a negative second lens group as a focusing lens group, a diaphragm, a positive third lens group, and a positive fourth lens group, in this order from the object.Upon zooming from the short focal length extremity to the long focal length extremity, all the lens groups move toward the image.The second lens group includes a first2asub-lens group, and a second2bsub-lens group, in this order from the object.The telephoto zoom lens system satisfies the following conditions:in-line-formulae description="In-line Formulae" end="lead"?1.6<fs/|f2|<2.1  (1)in-line-formulae description="In-line Formulae" end="tail"?in-line-formulae description="In-line Formulae" end="lead"?0.45<|f2bn|/f2bp<0.8  (2)in-line-formulae description="In-line Formulae" end="tail"?whereinfs: the focal length of the zoom lens system at the short focal length extremity;f2: the focal length of the negative second lens group (f2<0);f2bn: the focal length of the biconcave negative lens element of the second2bsub-lens group (f2bn<0); andf2bp: the focal length of the biconvex positive lens element of the second2bsub-lens group (f2bn>0).

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English language Abstract of JP 6-51202.
English language Abstract of JP 9-133865.

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