"PhilM" <com.am> wrote:
Only that with the 1.4x the 100-400 becomes a f6.1-8 and the 2x a f8.8-11
I think that many bodies require at least f5.6 to AF properly. You maybe
need to cover contacts on the TC to 'trick' it into letting you use that
combination and AF if light permits.
The IS will still function with the TCs.