The Speed Booster works by shrinking the image circle of your Canon EF lens down to better fit the smaller 16mm sensor. This has the effect of making the field of view of the lens 0.58x wider or, in other terms, reducing the crop factor of the camera from 2.88x to 1.75x. For example, a 30mm lens becomes an effective 52.5mm with this Speed Booster on a Blackmagic Pocket Cinema Camera instead of the 86.4mm effective view you'd have with a straight adapter. This is closer to the APS-C view of around 45/48mm for this particular lens example. Your Micro Four Thirds mount BMPCC will render less like a 16mm sensor and more like the larger APS-C or Super 35 sensor thanks to this Speed Booster, plus you have the benefit of using a wide variety of Canon EF lenses while retaining lens AF (from firmware v2.1) and image stabilization.

By concentrating the image circle from a lens, this Speed Booster also "brightens" the image – maximum lens apertures are increased by 1 and 2/3rd stops. As an example, this yields a maximum aperture of f/0.74 when using a Canon 85mm f/1.2L. This Speed Booster is powered by the camera body, so no additional power supply is needed. To reduce the drain on your camera's battery, it uses an efficient switched-mode power supply, which continually switches between on and off states and only draws power when it needs it. The Canon EF Lens to Blackmagic Pocket Cinema Camera Metabones T Speed Booster is a great tool for those using the Blackmagic Pocket Cinema Camera who want to also use a large selection of Canon EF mount lenses while getting that added benefit of a "boost" to both field of view and maximum aperture.

Please see the "Notes" section for important information about autofocus and lens compatibility.