Patent attributes
The present invention provides an optical option attachment ring comprising: a ring body into which a lens barrel is inserted; a clamping ring rotatably fastened on the periphery of the ring body; an elastic member arranged between the ring body and the clamping ring; and an abutting portion which is provided on the clamping ring and abuts on the elastic member according to the rotational position of the clamping ring to elastically deform the elastic member to cause at least a part of the elastic member to project further inwards than the inner peripheral surface of the ring body and to be positioned in a groove formed in the lens barrel.