Rear focusing zoom lens
AssigneeCanon Kabushiki Kaisha
InventorHiroki Nakayama
Life of this patent
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Abstract
A zoom lens having a first lens unit remaining stationary and having positive refracting power, a second lens unit having negative refracting power, a third lens unit having positive refracting power, a fourth lens unit having negative refracting power and a fifth lens unit remaining stationary and having positive refracting power to perform zooming by moving at least the second lens unit and the fourth lens unit and to perform focusing an infinite object to a nearest object by moving the fourth lens unit toward the image surface.
Claims35
A rear focusing zoom lens system, comprising:
- a first lens unit remaining stationary and having positive refracting power;
- a second lens unit having negative refracting power;
- a third lens unit having positive refracting power;
- a fourth lens unit having negative refracting power;
- and
- a fifth lens unit remaining stationary and having positive refracting power, which are disposed in this sequential order when viewed from an object,
- wherein at least said second lens unit and said fourth lens unit are moved to perform zooming, and said fourth lens unit is moved toward an image surface to perform focusing from an infinite object to a nearest object.
A rear focusing zoom lens system, comprising:
- a first lens unit remaining stationary and having positive refracting power;
- a second lens unit having negative refracting power;
- a third lens unit remaining stationary and having positive refracting power;
- a fourth lens unit having negative refracting power;
- and
- a fifth lens unit remaining stationary and having positive refracting power, which are disposed in this sequential order when viewed from an object,
- wherein at least said second lens unit and said fourth lens unit are moved to perform zooming, and said fourth lens unit is moved to perform focusing, and
- wherein said fourth lens unit is moved toward an image surface to perform focusing from an infinite object to a nearest object.
A rear focusing zoom lens system, comprising:
- a first unit having positive refracting power;
- a second unit having negative refracting power;
- a third unit having positive refracting power;
- a fourth unit having negative refracting power;
- a fifth unit remaining stationary and having positive refracting power, which are disposed in this sequential order when viewed from an object,
- wherein said fourth unit is moved toward an image surface to perform focusing from an infinite object to a nearest object, and said third unit consists of a single lens, and
- wherein zooming is performed by moving said second unit and said fourth unit.
A rear focusing zoom lens system, comprising:
- a first unit having positive refracting power;
- a second unit having negative refracting power;
- a third unit having positive refracting power;
- a fourth unit consisting of one of (i) a single lens and (ii) a plurality of lenses bonded together, and having negative refracting power;
- and
- a fifth unit remaining stationary and having positive refracting power, which are disposed in this sequential order when viewed from an object,
- wherein said second unit and said fourth unit are moved to perform zooming, and said fourth unit is moved along an optical axis toward an image surface to perform focusing from an infinite object to a nearest object, and
- wherein said fourth unit is moved to have a convex locus facing the image surface when power is varied from the wide angle end to the telescopic end.
Dependencies are inferred from the claim text.