John Sheehy wrote in post #17251557
I tried the 300/4L IS with the 2xIII and it focused, but obviously slower than without the TC, so those big whites should do much better, I'm sure, as they are sharper and have better AF mechanisms.
I'll post my results with the 500/fL II using the 2x III once I actually get my 7D2 (as I've vented earlier in this thread a few times, I still don't have it in my hands due to Amazon dropping the ball).
I never used the 2x with the 7D because of the inability to AF...
digital paradise wrote in post #17251578
I have the 2xII which I'll try out. Both Canon and Sigma. I could crop so much with my 7D I just stopped using my 1.4. I might have to look into a 2xIII if the IQ is significantly better and I like the results with my 2x . I'll have to do some research.
I didn't notice a huge boost in IQ between the II and III versions of the 1.4x, but AF performance was definitely better. If the 2x isn't appreciably slower for AF than what I started with years ago (a 1.4x II, a 300f4, and a 30D), I'll be happy.
TeamSpeed wrote in post #17251712
That wasn't his shot, it was from Arthur Morris (Canon Explorer of Light Birder), who uses some big white lenses and 2x MKIII teleconverters.
IIRC, Arthur also used to stack multiple TCs using extension tubes (and obviously, manual focus). He still got amazing quality images.