"Canon EF to BMCC mount T Speed Booster adapters designed exclusively for the Blackmagic 2.5k Cinema Camera (BMCC). Note that the new Speed Boosters will only attach to Blackmagic cameras equipped with a Micro-4/3 mount. They cannot be attached to standard Micro 4/3 cameras. The new 0.64x Speed Booster reduces the full-frame crop factor of the BMCC from 2.39x to 1.53x, thus effectively transforming it into a Super-35 format cine camera. In addition, the speed of any attached lens is increased by 11/3 stops, with a maximum output aperture of f/0.80. Increase maximum aperture by 11/3 stop. (with a maximum output aperture of f/0.80) Increase MTF Makes lens 0.64x wider Optics designed by Caldwell Photographic in the USA (patent pending) When using with ""passive"" (without electronic control pin) MFT camcorders/cameras, such as BMCC 2.5K MFT and Digital Bolex D16 MFT, the Speed Booster must be powered by external power source via Micro-USB socket. Input Voltage is 5V DC. (Battery is NOT included in the box ) When using with ""active"" (with electronic control pin) MFT camcordrs/cameras, such as BMPCC MFT, the Speed Booster can be powered by camera body. no external power source required Build-in electronics to control lens aperture The Lens aperture is set by the dial button on the adapter High performance 32-bit processor and efficient switched-mode power supply The tripod foot is detachable and compatible with"