T-ring(M42) adapter telescope parts type: T-ring for CANON EOS ,MINOLTA ,OLYMPUS4/3 ,PENTAX-U ,PENTAX-K ,NIKON ,SONY T-ring ... -ring for PENTAX-U M42x0.75 T-ring for PENTAX-K M42x0.75 T-ring for NIKON M42x0.75 T-ring ... for OLYMPUS4/3 M42x0.75 T-ring(M42) adapter astronomical telescope parts