Canon’s innovative new EF – RF optical adapter, the Mount Adapter EF-EOS R 0.71x, converts light transmission from full-frame to the Super 35mm image format. It extends the angle of view and optical sensitivity, while seamlessly integrating with the camera’s optical corrections. This unit greatly expands the list of compatible lenses by including Canon’s renowned line of EF lenses.
In addition to the flanges of the RF mount, four screws securely attach the adapter to the EOS C70 camera. Once mounted, the adapter maintains a similar angle of view of your full frame lenses on the Super 35mm sensor, while boosting the speed of the attached lens. The adapter also carries all EF information through to the RF contacts, so, on certain EF lenses*, full DPAF and metadata will be available with EOS C70 camera, working much as they do on a native EF mount.
*RF lenses, EF-M lenses, and EF-S lenses are excluded from the EF lens series. Compatible EF lenses are "EF16-35mm F2.8L III USM", "EF24-70mm F2.8L II USM" and "EF24-105mm F4L IS II USM". As of September 24, 2020. With the firmware update provided free of charge, the corresponding lenses will be expanded sequentially. Even if you do not update the firmware, you can use the EF lens, but it is recommended to use the firmware update in order to effectively use the function linked with the camera.