camera adapter ring thread diameter:37-30.5mm 37-30mm,37-34mm,52-58mm,55-58mm,etc. camera accessories lens adaptor step ring Step ... size of step-up adapter ring and step-down adapter ring for your selection.Camera adapter ring is used between camera(or projector) and lenses ... mm,37-30mm,37-34mm,52-58mm,55-58mm,etc.Adapter ring /Lens adaper /Camera adapter camera adapter ring37mm