To realize appropriate exposure even when the opening amount of a diaphragm is changed at the time of shift and tilt operation or at the time of zoom operation by correcting the driving amount of a diaphragm mechanism by a driving device based on the detected result by a detecting device.

A shift amount and a tilt amount are detected by a shift amount detecting device 18 and a tilt amount detecting device 19 and the detected result is transmitted to a rotational angle processing circuit 14. The storage device of the circuit 14 calculates the correction driving amount of a diaphragm blade 17 corresponding to the rotational angle of an interlocked disk member 10 and corresponding to the shift amount and the tilt amount based on the corresponding data of the correction amount of the driving amount of the blade 17 with respect to the shift amount and the tilt amount. An electromagnetic diaphragm driving control circuit 15 transmits a necessary driving instruction to an electromagnetic diaphragm unit 16 based on the value of the correction driving amount transmitted from the circuit 14. The unit 16 drives the blade 17 by the correction driving amount by using a motor in the unit so as to change the opening amount D formed by the blade 17.