Yes, Canon launched an RF 400/2.8 and a 600/4 that are the MkIII optics (possibly different AF motors) with the EF-RF adapter bolted on, and they launched an RF 800/5.6 and a 1200/8 that are those same lenses, respectively, with a built-in, lens-specific 2x TC in the optical design.
I'm planning on going to NZ or up north in Europe next year and I really need a fast UWA prime. 16mm would be better but I probably don´t want to pay that kind of money if it is f1.4You say that like it's a bad thing. That said, I don't think it can be, since the TC on RF is significantly closer to the sensor. Maybe the difference isn't visible on a little lens formula diagram, but I'd guess at a minimum the last couple of groups are very slightly tweaked in order to hand the different TC, even if the diagram generally looks identical. The change could well be less than a pixel's worth on those relatively low-resolution formula diagrams.
The RF design for the 800/5.6 is quite different from the EF 800/5.6, since the EF version was designed as an 800/5.6 lens whereas the RF is actually a 400/2.8 with a 2x TC included (I drew a magenta box around it).
Maybe a RF 200-500 mm f4.5 DO lens??? I would be thrilled because it would be shorter and lighter than a non-DO lens.
