Smooth surface for effortless mount,infinity focus allowed.The adapters are precision made to insure the perfect fit. | Made of brass and aluminum (not plastic), anodized aluminum construction. | Compatible Cameras (Including, but not limited to): Olympus PEN E-PL1, E-PL1s, E-PL2, E-PL3, E-P2, E-P3, E-M, OM-D, E-M5, E-M10, Panasonic Lumix DMC-G1, G2, G3, G10, GX1, GH1, GH2, GF1, GF2, GF3, GF5, GH4, Panasonic AG-AF100 Mirrorless Digital Cameras, Black Magic Pocket Cinema Camera (BMPCC). | As Canon's EOS lenses are electronically controlled,most Canon EF mount lenses do not feature a manual aperture ring,so when used on our EOS-M4/3, which is a full manual operation adapter ring, the aperture could not be transfered to the camera, it will stop down to its smallest f/stop by default. | Adapting full-frame lens to APS-frame or M4/3 frame camera, it will magnify the focal length by 1.6 on Canon, 1.5 on Nikon and Sony,2.0 on M4/3 camera