Patent ID: 7092155

Claim:
An optical device comprising: an optical system mount plate on which an optical system is mounted; a casing enclosing said optical system mount plate and the optical system; a screw-hole forming part that is provided on a bottom of said casing and including a screw hole configured to receive a screw provided on a tripod head which can threadedly fit in the screw hole of said screw-hole forming part, said screw-hole forming part and at least one portion of said bottom of said casing being engaged with said optical system mount plate so as to counteract a rotational tightening force applied to said screw-hole forming part when the screw is threadedly tightened in said screw-hole forming part; and a protrusion projecting from said bottom of said casing and extending in an axial direction of the screw hole, wherein said protrusion is engaged in a hole formed in the optical system mount plate.