The present invention alters the frequency response of an optoelectronic device to match a driver circuit that drives the optoelectronic device. The body controller performs control to send the interchangeable lens a command to set the interchangeable lens to a synchronous mode in which operation of the interchangeable lens is controlled in synchronization with the synchronizing signal and a command to set the interchangeable lens to an asynchronous mode which is a mode other than the synchronous mode. The regulating knob includes a tube portion, a front end of which is formed into steps gradually lowered in a circumferential direction, and hollow projections spaced along an inner wall surface corresponding to the steps for engaging with the steel ball on the connector to locate the regulating knob in place.