Patent ID: 8711490

Claim:
A lens system, comprising: a lens unit; a drive unit for driving the lens unit in an optical axis direction, configured such that any one of a first maximum current value serving as a normal state and a second maximum current value larger than the first maximum current value can be set as a maximum current value of a drive current supplied for driving; a detector for detecting a position of the lens unit in the optical axis direction; a lens operation unit for operating driving of the lens unit in the optical axis direction; a computing unit for computing a positional command value and optionally a speed command value, both for controlling driving of the lens unit based on a signal input from the lens operation unit, and controlling the driving of the lens unit; and a timer for measuring a time during which the second maximum current value is continuously set as the maximum current value in the drive unit, wherein in a case in which a difference between the positional command value and a lens position is larger than a predetermined positional difference threshold, and/or a difference between the speed command value, when further computed by the computing unit, and a drive speed is larger than a predetermined speed difference threshold, and the time measured by the timer has not exceeded a predetermined high-current maximum time which is a predetermined maximum value of time during which the second maximum current value can continuously be set as the maximum current value, the computing unit sets the second maximum current value as the maximum current value in the drive unit; and otherwise, the computing unit sets the first maximum current value as the maximum current value in the drive unit.