Patent attributes
A diaphragm control apparatus in a camera body includes a stepping motor, a lead screw thereof, wherein a slider is driven by the lead screw, a position detector, and a controller. When the stepping motor is in a free state, the slider allows a diaphragm operatively-associated rod to move to an initial position. The controller detects the slider origin position when the stepping motor is in the free state and drives the stepping motor stepwise to move the slider away from the origin position against a biasing force of a resilient biaser, and drives the stepping motor stepwise to move the slider toward the origin position while detecting the slider position; and sets an initial excitation pattern of the stepping motor upon a distance from the detected slider position to the origin position becoming less than a slider moving distance for one step of the stepping motor.
