Zoom lens of the internal focus type
AssigneeCanon Kabushiki Kaisha
InventorsChiaki Terasawa, Kiyoshi Fukami, Jun Hosoya, Shigeru Oshima
Life of this patent
Estimating the term…
Abstract
A zoom lens is disclosed comprising a front lens unit, an intermediate lens unit having two lens sub-units with their axial separation varying for zooming purposes, and a rear lens unit, wherein at the wide-angle end, focusing is performed by moving at least the rear lens unit, and, at the telephoto end, focusing is performed by moving the intermediate lens unit and the rear lens unit, whereby the amount of focusing movement of the intermediate lens unit from an infinitely distant object to an object at a certain short distance is greater at the telephoto end than at the wide-angled end.
Claims14
A zoom lens system comprising:
- from front to rear,
- a front lens unit;
- an intermediate lens unit having two lens sub-units with their axial separation varying for zooming;
- and
- a rear lens unit having a plurality of lenses,
- wherein at the wide-angle end, focusing is performed at least by moving one lens of said rear lens unit, and at the telephoto end, focusing is performed by moving said intermediate lens unit and said one lens of said rear lens unit, wherein an amount of focusing movement of said intermediate lens unit for focusing from an infinitely distant object to a certain close object is greater at the telephoto end than at the wide-angle end.
A zoom lens having an optical axis, comprising:
- a first lens unit having a positive refractive power;
- a second lens unit following said first lens unit, having a negative refractive power and moving along the optical axis for zooming;
- a third lens unit following said second lens unit and moving along the optical axis for zooming;
- and
- a fourth lens unit following said third lens unit and having a plurality of lenses,
- wherein said zooming onto an infinitely distant object is performed by moving said second and third lens units while keeping said fourth lens unit stationary, and zooming onto a finitely distant object is performed by moving said second lens unit, said third lens unit and at least one lens of said fourth lens unit.
A zoom lens system, comprising:
- a variator portion, having a plurality of lens units, for zooming by changing interspaces of the lens units,
- a rear lens unit located behind said variator portion and including a focusing lens,
- wherein the focusing is effected by moving at least said focusing lens at a wide angle end, while at a telephoto end the focusing is effected by moving said focusing lens and lens units of said variator portion, and a focusing movement amount of said lens units of said variator portion is larger at the telephoto end than at the wide angle end.
Dependencies are inferred from the claim text.