Bayonet type fixing device having annular members and a zoom lens having the same

摘要

A bayonet fixing device includes a cylindrical member; an annular member attached to one end of the cylindrical member; and a retainer ring attached to the cylindrical member to fix the annular member to the cylindrical member. The cylindrical member includes engaging lugs and insertion areas which are alternately arranged along the circumference at one end of the cylindrical member; grooves formed behind the engaging lugs; and recesses formed behind the grooves. The annular member includes a plurality of projections which are respectively fitted into the recesses via the insertion areas and the grooves. The retainer ring includes engaging blades which are fitted into the grooves via the insertion areas to be positioned between the engaging lugs and the projections in an axial direction of the cylindrical member.