Patent ID: 7885534

Claim:
A light-amount adjusting system comprising: a light-amount adjusting unit configured to change a size of an aperture through which light passes, the light-amount adjusting unit including a biasing member biasing a light-shielding member that changes the size of the aperture, in one of an aperture opening direction and an aperture closing direction; an actuator configured to drive the light-amount adjusting unit; a detector configured to detect an aperture state of the light-amount adjusting unit; a deviation signal generator configured to generate a signal corresponding to a deviation between a target aperture state of the light-amount adjusting unit and an aperture state thereof detected by the detector; a driving signal generator configured to provide an offset to the signal corresponding to the deviation to generate a driving signal for driving the actuator; and a filter configured to perform low-pass-filter processing on the driving signal, wherein an output from the filter is used as the offset.