1D Mk iv and 1.4x Mk 2 extender.

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.

your extender has long been obsolete, you need to purchase 1.4X III if you plan to shoot flight. Having said that the slow zoom+TC combination won't fair well for flight on a 1D4.

Thanks for replying Arash although I don't quite understand your answer. You say that my extender is obsolete and yet in another post you advise that the Mk 3 extenders only communicate between 1DX and super telephoto's and so no advantage is gained with any other combination. I take it that there will be no advantage in focusing ability between 7D2 and 1D4 with my lens and extender combination?

Hi David I think you're confusing the following two topics.

Series III extenders have a micro controller that can talk to the CPU in the series II lenses for better AF. This is true with any camera body including 1D4. The optics is also improved when used with zoom lenses.

the 1DX series can enable high speed AF mode at f/8 when a series III extender is attached to a series II lens. This doesn't apply to you since you plan to use a 1D4


so you can still benefit from upgrading your TC but overall it will still be quite slow and frustrating for flight shots.

Best

Thanks for the explanation Arash. I understand now.

Regards. David.