"Metabones Speed Booster mounts between a mirrorless camera and a SLR lens. It increases maximum aperture by 1 stop (hence its name), increases MTF and has a focal length multiplier of 0.71x. For example, the Canon EF 85mm f/1.2L II lens becomes a 59mm f/0.9 lens on a Sony NEX camera, with increased sharpness. The faster F-stop allows for shallow depth-of-field and a lower ISO setting for decreased noise. Speed Booster is also particularly pertinent to ultra-wide-angle SLR lenses. The combined focal length multiplier of Speed Booster and an APS-C mirrorless camera is approximately 1.09x, making the combination almost "full-frame". Full-frame ultra-wide-angle SLR lenses largely retain their angle-of-view on an APS-C mirrorless camera when Speed Booster is used. The optics of Speed Booster is designed by Brian Caldwell, PhD, a veteran of highly-corrected lens designs such as the Coastal Optics 60mm f/4 UV-VIS-IR APO Macro lens with exemplary MTF performance (focusing done with visible light requires no correction whatsoever for the full spectrum from UV to IR). To clear up any potential confusion, this is NOT Sony Alpha, but Alpa of Switzerland. You will most likely be using the Kern Macro Switar 50mm f/1.8 or f/1.9 apochromat lens on this adapter. |Increase maximum aperture by 1 stop|Increase MTF|Makes lens 0.71x wide|The tripod foot is detachable and compatible with Arca Swiss, Markins, Photo camball heads.|Both camera-side and lens-side of the adapter are made of brass, precision-machined and plated with chromium|Satin surface finish - just like your OEM lens and camera mounts|Precise fit and solid connection - lens has no play, gap or wiggling when mounted on adapter and no adjustments are required to fit your lens|Designed to reach infinity focus while maintaining the correct registration distance required to maintain optical quality of CRC lenses or lenses with floating elements"