Canon RF 100-300 f/2.8 IS USM

[neuroanatomist]

Thanks John.....I came across these two images of Bryan's (here and here) with the 100-300 f/2.8 with a 2x TC which are plenty sharp, IMO. The typical fall off in IQ with a 2x TC does not seem to be happening here. But, I was wondering how fast the AF is? Do you see the usual fall off in AF?

I think it slows down a little with the 2x, but the AF is so fast natively that any difference is barely perceptible.