The latest member of its award-winning Speed Booster family of DSLR (digital single-lens reflex) to mirrorless lens mount adapters, EF-EOS M Speed Booster ULTRA 0.71x. Full-frame Canon EF-mount lenses are now one stop faster, 0.71x wider and with increased MFT (note 1) on Canon EOS M cameras. The 4k/UHD video crop on EOS M50 can also be mitigated with third-party APS-C lenses using this Metabones Speed Booster. Some Canon EF-S lenses may be modified to fit on the Speed Booster but Metabones cannot be held liable for any issues arising from modifications. Using APS-C lenses with Speed Booster for still photography or full HD videography may result in vignetting. Ever since the first Speed Booster was introduced, there have been DIY attempts to modify it to fit EOS M cameras. The turnkey solution Metabones now offers adds a number of refinements: The optical housing is redesigned for perfect fit on EOS M.The EXIF metadata is changed to reflect the faster aperture (note 2) and shorter focal length. The autofocus speed of the lens is adjusted and optimized for the change in focal length and aperture to ensure the best performance. This is especially important for dual-pixel autofocus (DPAF) in video mode.A 'chip' mode is added so that the user may store the metadata of a fully mechanical manual lens in the adapter.A LED indicates operational status of the Speed Booster. Since both the lens and the camera speak the same protocol most features are supported with the exception of lens aberration correction, which is automatically turned off.