EF 400mm f2.8 IS iii (adapted) vs RF - Real world testing or experience with mirrorless bodies

[mikerigney]

Hi all, first post here. It's been a few years since the RF 400mm f2.8 was released and I still cannot find any real-world testing or first-hand experience between the EF IS iii version and the re-mounted RF version. There was a lot of speculation about performance between these near-identical lenses but no real world information.

Has anyone found a good comparison? Not looking for specs or speculation. Plenty of that already. Specifically looking for autofocus speed comparisons - if the RF mount has any advantage over the adapted EF. Bonus points for performance with the 1.4 and 2.0 TCs. 

I'm shooting R5 with the EF 400mm f2.8 IS ii right now.

Thanks!

[ebiggs1]

I can't help much since I have never used even the EF version of the 400mil let alone used the RF model. However,  that said all the other RF lenses I have tried or used have either equaled or surpassed their EF counter parts in every way. So, I see no reason to see why this would not be true with the 400mm.

You may debate whether other makers have better digital cameras but there is no dispute that Canon is the world leader in lenses.

[mikerigney]

Incredible