Flange 20 mm · Full frame 1× · APS-C 1.6×
Canon launched the RF mount in September 2018 with the EOS R, then added APS-C bodies and RF-S lenses in 2022, starting with the EOS R7 and R10. Canon's APS-C sensors crop by 1.6 rather than the usual 1.5. At 20mm the RF flange is the longest of the mirrorless mounts here, still far shorter than any SLR lens needs. Canon makes adapters for its EF lenses, but FD lenses never fit EF, so they need a direct FD to RF adapter.