Teleconverters RF vs EF

Abbott Schindler wrote:

If I understand you correctly, you want to try this:

R series camera - RF Extender - RF-EF adapter - EF big white

This is a nonstarter: the RF Extender won't fit into the RF end of the adapter.

If you want to use an Extender with an EF big white, you need to do this:

Camera - RF-EF adapter - EF Extender - EF big white.

OTOH, I've tested, and extension tubes work both ways:

Camera - RF-EF adapter - EF extension tube - EF lens

Camera - RF extension tube - RF-EF adapter - EF lens

Yes, see my post above when I tried to pair my wife's RF teleconverter to the RF to EF adapter - it just doesnt fit

The question is though how does adding space between the teleconverter and the lens affect image quality.  See my post above.  That is effectively what Canon did with the RF 600 and RF 400 lens design by incorporating the RF to EF adaptor into the lens.

I.E., what does this combo do:

Camera - RF Tele - extension tube - lens.

My EF 500 F4 lens does not have any spacer added (between lens and tele) when I add a EF teleconverter to it.  Lets say that the RF to EF adapter is approximately a 7/8" spacer.  Since Canon designed the RF 600 F4 and the RF 400 F2.8 with a built in RF to EF adapter, when adding a RF teleconverter to either of those 2 lenses, there is a 7/8 inch spacer between lens and tele.

The question is, with the design of the RF 600 F4 and RF 400 F2.8, how does the extra space between lens and teleconverter affect image quality?

Shawn