Bianchi wrote in post #19157206
Have you tried the 1.4 added to the 150-600 on the R5, if so, was AF as responsive, as if it was on natively?
I don't have that lens, but with the Sigma 100-400/5-6.3, reporting TCs slow down AF significantly during those long-haul large changes in focus distance, contrasted to my 400/4DO II, which doesn't seem to slow down much at all with either a Kenko Pro 300 DG 1.4, or the Canon 2xIII. Before I updated the Sigma firmware a couple of weeks ago, I could use it with a Tamron 2x with taped pins (I am not inclined to put tape on the 2xIII), and it AFed pretty fast, but was more prone to go off focus after initially locking on, but refocused pretty fast. I think that 1.4x worth of non-reporting can help the speed without the side effect, but 2x is a bit much for 99%-lockon. The EF TC protocol is a pain in the butt. You should be able to have a TC that reports EXIF correctly, even stacked with other TCs, and have options to vary the speed regulator to match your system and your needs. The R5 and R6 open up TC AF opportunities quite a bit, at the level of potential, but that potential is very difficult to realize with the antiquated protocol, which assumes lame/dead DSLR AF with higher f-numbers (at least for EF lenses and TCs - I don't know the TC communication situation with RF lenses).
