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US 7,248,418 B2Granted
Zoom lens system and image pickup apparatus including the same
AssigneeCanon Kabushiki Kaisha
InventorsAkihiro Nishio, Shinji Yamasaki
Life of this patent
Estimating the term…
Abstract
A zoom lens system includes a first lens unit, a lens unit having a positive optical power placed on an image side of the first lens unit, and a lens unit having a negative optical power placed on the image side of the lens unit having a positive optical power. In the zoom lens system, the lens unit having a negative optical power is closest to the image side. A compact zoom lens system is obtained by adequately setting the movement of each lens unit during zooming and the optical power of each lens unit.
Claims8
A zoom lens system comprising:
- a first lens unit including a reflective member that deflects an optical path;
- a lens unit having a positive optical power placed on an image side of the first lens unit;
- and
- a lens unit having a negative optical power placed on the image side of the lens unit having a positive optical power, the lens unit having a negative optical power is positioned closest to the image side in the zoom lens system, wherein a distance between the first lens unit and the lens unit having a positive optical power and a distance between the lens unit having a positive optical power and the lens unit having a negative optical power vary during zooming from the wide-angle end to the telephoto end, and wherein when Fe is the focal length of the lens unit having a negative optical power and Fw is the focal length of the overall system at the wide-angle end, the following expression is satisfied:
- 0.8<|Fe/Fw|<2.5.
2 more elements
Dependencies are inferred from the claim text.