Canon has officially announced the first professional super-telephoto lenses with the RF 400mm f/2.8L IS USM and RF 600mm f/4L IS USM. Both of these lenses are pretty much identical to to their EF mount brothers.
The Canon RF400mm F2.8L IS USM and Canon RF600mm F4L IS USM are both designed to be optically identical to their EF counterparts. The RF400mm and RF600mm weigh in at 6.37 and 6.81 pounds with a minimum focusing distance of 8.2 and 13.8 feet, respectively. Both lenses share many of the same critical features that help professional high-end super-telephoto lenses stand out from the crowd. Those features include:
Ideal for a wide variety of shooting situations, including sports, aviation, trains, automotive, and wildlife, such as birding.