PURPOSE: To adjust the position of a lens by interlocking with switching of a mode by locking a front lens group to a reference position at the time of AF mode and executing an AF operation, and automatically resetting a rear lens group to the reference position after the lock is released.

CONSTITUTION: The lens system is constituted of a front lens group 2, a zoom lens group 3 and a rear lens group 4, and at the time of manual mode, focusing is executed by the front lens group 2, and at the time of AF mode, focusing is executed by the rear lens group 4. In such a state, at the time of AF mode, by locking the front lens group 2 to a reference position, an AF operation is executed, and by releasing the lock, the rear lens group 4 is reset to the reference position and the manual mode can be executed. In such a way, the position adjustment of the rear lens group or the front lens group 2 can be executed by interlocking with a switching operation of a photographing mode, and the mode can easily be switched.