Canon Identically Ports its 400mm f/2.8L and 600mm f/4L from EF to RF
Canon has announced the coming availability of the RF400mm f/2.8L IS USM and Canon RF600mm f/4L IS USM, which it admits are optically identical to the original EF designs. The lenses look pretty much identical, save for what appears to be a bright silver built-in RF adapter.