Patent ID: 8780260

Claim:
An imaging device comprising: an image sensor; an engagement member which is an annular or cylindrical member provided between a fixed lens mount unit and a first optical filter fixedly installed on a subject side of the image sensor, an annular or cylindrical filter holding member for holding a second optical filter and disposed in abutting relationship with the engagement member and having a stepped portion cooperating with the engagement member to form a groove in an inner circumferential direction, said filter holding member having a convex portion formed on an outer periphery of the filter holding member to be received by and fit within said groove, the engagement member engaging the filter holding member in an attachable/detachable manner, the engagement member having a notch, formed on a side surface on a side of the lens mount unit of the groove, for guiding the convex portion to the groove; and a stop element disposed within the groove and adapted to be contacted by the convex portion when the filter member is rotated in the groove, thereby restricting rotation of the convex portion around an optical axis.