I have almost made up my mind to trade in my 7D Mk2 for a 1D Mk4 and there is just one thing I would like to know from experienced 1D Mk4 users please. The 7D2 takes the 1.4x Mk2 extender well for static bird shots but I have not found it to be of any use for BIF, it just wont focus on a moving bird. How does the 1D Mk4 take the 1.4x extender for BIF shots? Any observations/advice very welcome.
PS. The lens I am using is the 100-400 Mk2.