Disclosed is an optical filter switching apparatus used in an optical
instrument for converting externally input image information into video
image information and outputting the video image information. The
apparatus comprises: an optical filter holding section holding a first
optical filter and a second optical filter; an actuator having a rotary
solenoid which rotates between a first position and a second position. A
rotational power transmission section transmits the rotational force of
the rotary solenoid to the optical filter holding section; and a
microprocessor controls the rotary solenoid of the actuator in accordance
with at least one external input signal and the power level of the video
image information. The rotary solenoid is rotated to at least one of the
first and second positions. The optical filter switching apparatus
directly drives the optical filter holding section using an actuator
provided with a rotary solenoid, whereby the optical filter holding
section is switched to a first or second optical filter setting position.