EB-1 wrote:
I checked my records and I rented 5x 100-500s plus own one. They have been rather consistent. Maybe one was slightly worse. The same RF 1.4x works great with the 600/4 RF. I supose there are some differences in expectations. (The 500/4 IS II with 1.4x III at f/7.1 is like night and day better.) On the 100-500 f/11 effective is better than f/10 for contrast but not more resolution. I suspect that f/10 has too much diffraction already at 45MP
EBH
It is also very possible that my 'excellent' appraisal is coming in comparison with my older 100-400 L II x EF 1.4x II which was 'just ok'
