Extending the range of compatible lenses while maintaining their original field of view, the Canon Mount Adapter EF-EOS R 0.71x permits attaching EF-mount lenses to RF-mount cine and mirrorless cameras. Intended for cameras featuring a Super 35 sensor size, this adapter also incorporates an optical system to increase the effective angle of view by 0.71x, reducing the effects of a full-frame to Super 35 crop factor and increasing the maximum aperture performance by one stop. Electric contacts are also incorporated into the adapter's design and maintain full communication between the camera and lens, as well as support metadata transmission and use of Dual Pixel AF with select Canon EF lenses. Also, the adapter has been specifically designed for the EOS C70 cinema camera and features four screws and a split locking collar to ensure a secure attachment.