or be absorbed but in rare cases it can enter the imaging device 32 after reflecting again on the end face of the bayonet type mount projection 22 placed on the lens barrel 20 this second catoptric light can hit at the inner surface of the camera body 30 if reflecting regularly on the end face of the bayonet type mount projection 22 but actually it rarely reflects regularly since there is microasperity on the end face of the mount projection 22 due to machine process when the second catoptric light 52 b and 52 c enter the imaging device 32 it is possible to become a ghost or a flare to deteriorate picture quality note that the light ray 50 can reflect on the imaging device 32 and also in the case of a silver salt film camera on the surface of the film in the end face in the optical axis direction of the barrel side fitting part 21 the projection 22 has a broader width in the radial direction where more catoptric light may hit to easily increase ghosts and flare therefore in the present embodiment the above described configurations of the bayonet type mount projections 12 and 62 solve the above problems hereinbelow the arranged position of the mount projections 12 will be explained an explanation on the mount projections 62 will be skipped since they have the same arranged position as the mount projections.