Zoom lens having an image stabilizing function
AssigneeCanon Kabushiki Kaisha
InventorsShingo Hayakawa, Kazuhiko Momoki
Life of this patent
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Abstract
A zoom lens is disclosed comprising, from front to rear, a first lens unit of positive refractive power, a second lens unit of negative refractive power, a third lens unit of positive refractive power, a fourth lens unit of negative refractive power, a fifth lens unit of positive refractive power and a sixth lens unit of negative refractive power, wherein, during zooming from the wide-angle end to the telephoto end, the air separations between the i-th and (i+1)st lens units are made to vary properly and the ratio of the focal length of the fourth lens unit to the longest focal length of the entire system is made to have a proper value. In particular, a zoom lens is disclosed wherein the second lens unit is made to decenter to stabilize the image.
Claims2
A zoom lens having an image stabilizing function, comprising, from front to rear, a first lens unit of positive refractive power, a second lens unit of negative refractive power, a third lens unit of positive refractive power, a fourth lens unit of positive refractive power and a fifth lens unit of negative refractive power, said second lens unit being arranged not to move for zooming and said fourth lens unit being arranged to move for zooming, and zooming being performed by varying a separation between said first lens and said second lens unit, a separation between said second lens unit and said third lens unit, a separation between said third lens unit and said fourth lens unit, and a separation between said fourth lens unit and said fifth lens unit, wherein said second lens unit is moved so that a component of movement of said second lens unit is perpendicular to an optical axis so as to correct shaking of an image,
- wherein the following condition is satisfied:
- 0.15<|fa/{square root over (fW·fT)}|<0.5
- where fa is the focal length of said second lens unit, and fW and fT are the shortest and longest focal lengths of the entire system, respectively,
- wherein said second lens unit includes two negative lens elements and one positive lens element, and
- wherein, during zooming from a wide-angle end to a telephoto end, said lens units are moved in such relation as to satisfy the following conditions:
- D1W<D1T
- D2W>D2T
- D4W>D4T,
- wherein
- D1W is the separation between the first lens unit and the second lens unit at the wide-angle end,
- D1T is the separation between the first lens unit and the second lens unit at the telephoto end,
- D2W is the separation between the second lens unit and the third lens unit at the wide-angle end,
- D2T is the separation between the second lens unit and the third lens unit at the telephoto end,
- D4W is the separation between the fourth lens unit and the fifth lens unit at the the wide-angle end, and
- D4T is the separation between the fourth lens unit and the fifth lens unit at the telephoto end.
Dependencies are inferred from the claim text.