Even more notably, the speed and bandwidth of the RF mount delivers faster and more responsive autofocus performance – the EOS R5 and EOS R6, for example, can acquire focus in a class-leading 0.05 seconds and then continue to track even fast-moving subjects across the entire frame.
Thanks to the RF mount, lenses can also take advantage of new focusing technologies. The RF 70-200mm F2.8L IS USM is the first lens to feature Dual Nano USM technology – it has two Nano USM motors, each driving different lens groups, working together to produce faster, more efficient focusing. The RF 400mm F2.8L IS USM and RF 600mm F4L IS USM super-telephoto lenses are the first in the RF lineup to feature a double power drive method, enabling cameras to focus faster than ever before. While the optics and mechanics of these two lenses are largely the same as the EF versions, their capabilities are next-level, as they take full advantage of Canon's revolutionary EOS R System and RF mount.
Technologies such as Nano USM, which combines the speed of traditional USM motors with the silent operation and smoothness of STM motors, are a real benefit particularly for videographers as well as sport or wildlife photographers, where they are shooting fast action and super-quiet, smooth focusing is required. What's more, the RF mount enables smoother aperture adjustments when you're shooting video, with all RF lenses supporting smaller increments of just 1/8 stop as compared to the 1/3 stop used for still photography, meaning less noticeable changes in brightness as you adjust the aperture while filming.
The RF mount's speed of connection even allows electronic focus breathing suppression to prevent the angle of view from changing as you focus. Non-RF cinema lenses tend to be very large because they incorporate a mechanical mechanism to help overcome focus breathing, but the RF mount, coupled with the use of Nano USM technology and floating focus groups, means this can now be done electronically, enabling a very compact lens design for video.