Extender EF 1.4x compatibility with Mount Adapter EF-EOS R

[rdominis]

I have an R6 body, a 70-200 f/4 RF lens, and an EF 1.4x teleconverter.

Does anyone know if adding an EF-RF converter to both sides (body and lens) allow the EF teleconverter to work? Thanks

[kvbarkley]

No, the teleconverter has to be right up to the lens. Remember, it has optics. And the EF-RF adapter only works one way, (lens)EF to (Body)RF, not (lens)RF to (body)EF.

[shadowsports]

Greetings, 

In addition to what kvbarkley posted, I'll add  that there is no TC compatible with the current RF 70-200 f4 or f2.8.

If Canon releases a RF 70-200 as an internal zoom which the mkII is rumored to be, you might see TC support.