Focus control method and focus control apparatus
AssigneeCanon Kabushiki Kaisha
InventorKazuki Konishi
Life of this patent
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Abstract
In a focus control method of acquiring focus information a plurality of times while moving a focus lens, and determining an in-focus position on the basis of the acquired focus information, whether the focus lens is to be moved toward the infinite end or the closest end is determined on the basis of a focus lens position, the focus information is acquired while moving the focus lens in the decided direction, the focus lens is stopped on the basis of the acquired focus information, and the focus lens is started from the stop position in a reverse direction.
Claims8
A focus control method of acquiring focus information a plurality of times while moving a focus lens, and determining an in-focus position on the basis of the acquired focus information comprising:
- a decision step determined by a control unit of, before acquiring focus information, deciding on the basis of a focus lens position whether the focus lens is to be moved toward an infinite end or a closest end;
- a focus information acquisition step determined by a control unit of acquiring the focus information while moving the focus lens in a direction decided in the decision step at a first predetermined velocity;
- a determination step determined by a control unit of determining whether the focus lens has passed an in-focus position or not on the basis of the focus information acquired in the focus information acquisition step;
- and
- a focusing step determined by a control unit of stopping moving the focus lens and starting moving the focus lens from the stop position in a direction reverse to the moved direction of the focus lens in the focus information acquisition step at a second predetermined velocity which is slower than said first predetermined velocity while maintaining timing of acquiring the focus information,
- wherein, in the focusing step, if it is determined that the focus lens has passed the in-focus position while moving toward the infinite end, the focus lens is immediately stopped, and if it is determined that the focus lens has passed the in-focus position while moving toward the closest end, the focus lens is stopped when the focus lens reaches the closest end.
A focus control apparatus which has a focus information acquisition unit, causes said focus information acquisition unit to acquire focus information a plurality of times while moving a focus lens, and determines an in-focus position on the basis of the acquired focus information comprising:
- a control unit that, before acquiring focus information, controls to decide on the basis of a focus lens position whether said focus lens is to be moved toward an infinite end or a closest end, cause said focus information acquisition unit to acquire the focus information while moving said focus lens in a determined direction at a first predetermined velocity, determine whether the focus lens has passed an in-focus position or not on the basis of the acquired focus information, stop moving said focus lens and start moving the focus lens from the stop position in a direction reverse to the previous moving direction at a second predetermined velocity which is slower than said first predetermined velocity while maintaining timing of acquiring the focus information,
- wherein if it is determined that the focus lens has passed the in-focus position while moving toward the infinite end, the focus lens is immediately stopped, and if it is determined that the focus lens has passed the in-focus position while moving toward the closest end, the focus lens is stopped when the focus lens reaches the closest end.
A computer-readable storage medium storing computer program codes realizing a focus control method comprising:
- a decision step of, before acquiring focus information, deciding on the basis of a focus lens position whether the focus lens is to be moved toward an infinite end or a closest end;
- a focus information acquisition step of acquiring the focus information while moving the focus lens in a direction decided in the decision step at a first predetermined velocity;
- a determination step of determining whether the focus lens has passed an in-focus position or not on the basis of the focus information acquired in the focus information acquisition step;
- and
- a focusing step of stopping moving the focus lens and starting moving the focus lens from the stop position in a direction reverse to the moved direction of the focus lens in the focus information acquisition step at a second predetermined velocity which is slower than said first predetermined velocity while maintaining timing of acquiring the focus information,
- wherein, in the focusing step, if it is determined that the focus lens has passed the in-focus position while moving toward the infinite end, the focus lens is immediately stopped, and if it is determined that the focus lens has passed the in-focus position while moving toward the closest end, the focus lens is stopped when the focus lens reaches the closest end.
Dependencies are inferred from the claim text.