jeep_daddy wrote:
I didn't think you could stack teleconverters like that. I know that I can't stack my 1.4x III and my 2x III. I used to have the II's and don't remember them stacking either. Did you modify them to get this to work? Also, if you use the 2x on that 100-400 at 400, it would be f/11. If you add the 1.4x on top of that it would be f/16???? Not sure but your EXIF says f/11
All three of my Quail photos have the EXIF @ f/11, whether it's the 2x II or 2x II and 1.4x II combined. That is the EXIF data. I just shot a photo a few minutes ago outside with the 1.4x II + 2x II = f/11. Only the Canon 1.4x II and the Canon 2x II can be combined and not the 1.4x III and the 2x III. No I did not modify them. Refer to Ken Rockwell's Canon EOS R review. You will see a sample moon photo using the Canon EOS R with the Canon 2x II and the Canon 1.4x II combined giving a total 1,120mm.
Ken Rockwell states the importance of using various 1.4xII and 2xII extenders together or separately with mirror-less cameras which is a big selling point. And yes, they auto-focus okay. But, not very fast.