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US 6,807,015 B2Granted
Focusing method for a zoom lens system
AssigneePENTAX Corporation
InventorsMasaru Eguchi, Takayuki Ito
Life of this patent
Estimating the term…
Abstract
A focusing method for a zoom lens system, including at least two lens groups, enables a portion of the zoom lens system to function as a focusing lens group over the entire focal length constituted by discrete focal length ranges. The portion of the zoom lens system, functioning as the focusing lens group, is changed to another portion thereof, in accordance with to the discrete focal length ranges.
Claims7
A focusing method for a zoom lens system comprising at least two lens groups, said focusing method comprising:
- operating a portion of said zoom lens system as a focusing lens group over the entire focal length range of the zoom lens system, the entire focal length range comprising a plurality of discrete focal length ranges;
- and
- changing the portion of said zoom lens system, which functions as said focusing lens group, from a first portion to a second portion, in accordance with the discrete focal length ranges,
- wherein said focusing lens group comprises a lens group with a transverse magnification that becomes −1 at a discrete focal length of said zoom lens system during zooming;
- and
- wherein said lens group functions as said focusing lens group in a discrete focal length range that does not include said discrete focal length range of the zoom lens system.
3 more elements
Dependencies are inferred from the claim text.