Varifocal optical system
AssigneeCanon Kabushiki Kaisha
InventorKeiji Ikemori
Life of this patent
Estimating the term…
Abstract
A varifocal optical system having at least two lens units A and B, the lens unit A being axially moved to vary the magnifying power, and, while it is moving, the refractive power of the lens unit B being continuously varied to compensate for the displacement of the position of the image surface caused by the variation of the magnifying power of the lens unit A, wherein variation of the refractive power of the lens unit B is made so as to maintain the constant position of a front principal point of the lens unit B when the lens unit A is in front of the lens unit B, or a rear principal point of the lens unit B when the lens unit A is at the rear of the lens unit B, relative to the image plane of the entire system.
Claims14
A varifocal optical system comprising:
- a movable lens unit movable along an optical axis, said movable lens unit having a positive refractive power;
- a compensation lens unit having principal points, said compensation lens unit having a variable negative refractive power which varies and compensates for the shift of an image surface resulting from the movement of said movable lens unit;
- an image plane;
- and
- means for varying the refractive power of said compensation lens unit in such a way that the principal point at said movable lens unit side of said principal points maintains a substantially same position relative to said image plane.
A varifocal optical system comprising:
- a movable lens unit of negative refractive power, movable along an optical axis;
- a compensation lens unit of variable positive refractive power, having principal points, and compensating for the shift of an image surface resulting from the movement of said movable lens unit;
- an image plane;
- and
- means for varying the refractive power of said compensation lens unit in such a way that the principal point at said movable lens unit side of said principal points maintains a substantially same position relative to said image plane.
Dependencies are inferred from the claim text.