Telephoto type objective
AssigneeCanon Kabushiki Kaisha
InventorHideo Yokota
Life of this patent
Estimating the term…
Abstract
A telephoto type objective comprising a front lens group and a rear lens group axially spaced apart from each other. The front lens group has a positive refracting power and which remains stationary during focusing. The rear lens group has a negative refracting power and is comprised of two movable lens members for focusing. When the two movable lens members are moved along the optical axis toward an image plane, the telephoto type objective is caused to focus an object at a near distance from its focusing on an object at a far distance with the resulting amount of movement of the rear lens member being larger than that of movement of the front movable lens group.
Claims13
A telephoto type objective comprising:
- a front lens group having a positive refracting power and which remains stationary during focusing, said front lens group being comprised of a plurality of lens members, and
- a rear lens group having a negative refracting power and positioned on the image side of said front lens group in axial alignment therewith, said rear lens group including at least two movable lens members arranged to be moved in the same direction along the common optical axis toward the image plane when the object distance is changed in focusing from infinitely distant object to close object with the resulting speed of movement of the front one of said two movable lens members being different from that speed of movement of the rear one.
A telephoto type objective comprising:
- a primary lens group having a positive refracting power and which remains stationary during focusing, said primary lens group being comprised of a plurality of lens member, and
- two movable sub-groups positioned on the image side of said primary lens group in axial alignment therewith to be movable for focusing in such a manner that the image side one of said two sub-groups moves at a faster speed than the object side sub-group.
Dependencies are inferred from the claim text.