Zoom lens
AssigneeCanon Kabushiki Kaisha
InventorsTsunefumi Tanaka, Keiji Ikemori, Masatake Kato, Kazuo Tanaka
Life of this patent
Estimating the term…
Abstract
A zoom lens which performs focusing by using part of a movable lens unit. In zooming, a lens unit V for changing the focal length of the entire system and another lens unit C for maintaining the constant position of an image plane move in certain relation to each other. For all objects in the focusing range, a part of either the aforesaid lens unit V or the aforesaid lens unit C is made to move to effect focusing at any station in the entire zooming range, thereby the zoom lens can be constructed in compact form.
Claims7
A zoom lens comprising:
- a variation lens unit axially movable for varying the focal length of the entire system;
- and
- a lens unit axially movable in accordance with movement of said variation lens unit to maintain the constant position of an image plane,
- said variation lens unit including a lens component which is movable over the entire zooming range and made movable to effect focusing from an infinity object to a close object, and another lens component which is held stationary during focusing, said two lens components moving in different paths during the zooming.
A zoom lens comprising:
- at least one variator lens unit axially movable for varying the focal length of the zoom lens;
- and
- at least one compensator lens unit axially movable in accordance with movement of said variator lens unit to maintain the constant position of an image plane,
- one lens part of said variator lens units includes a plurality of lens elements, part of said lens elements when in focusing being moved, over the entire zooming range, to effect focusing from an infinity object to a close object, said lens elements moving in different paths during the zooming.
A zoom lens comprising:
- a first lens unit having a positive power which is stationary during zooming and focusing;
- a second lens unit arranged on the image side of said first lens unit upon zooming to move to vary the image magnification and having a negative power, said second lens unit being including, from front to rear, a first lens part and a second lens part, wherein by moving either one of said first lens part and said second lens part, focusing is performed from an infinity object to a close object in the entire zooming range, said first lens part and said second lens part moving in different paths during zooming;
- a third lens unit arranged on the image side of said second lens unit upon zooming to move to maintain the constant position of an image plane and having a positive power;
- and
- a fourth lens unit arranged on the image side of said third lens unit to be stationary during zooming and focusing, and having a positive power.
A zoom lens comprising:
- a front lens unit stationary during zooming and focusing;
- a plurality of movable lens units arranged on the image side of said front lens unit and movable in a predetermined relation to each other to change the focal length of the whole lens system and to maintain the image plane at a constant position;
- and
- a rear lens unit arranged on the image side of said movable lens units and stationary during zooming and focusing, one of said movable lens units having a plurality of sub-units which move in different paths during zooming with one of said sub-units moving along the optical axis to cause the zoom lens to focus from an infinity to a close object.
Dependencies are inferred from the claim text.