jxsq wrote:
Here is my personal experience on AF speed,
1. + EF 1.4x II
Still very fast, very close if not at 135L and 400L level.
Based on several years of fast action photography with both, I can tell you that bare 300 f/2.8 IS is not as fast to focus as 135L, not even as 400 f/5.6 in decent light, let alone with the 1.4xTC.
