5D3 focus issue with 100-400 (outer points)

Not sure really where to start. Previously owned a 7d & coupled together with the 100-400 was fantastic & never missed focus in a1 servo on all 19 points. Have now changed to a 5D3 & am having problems with it focusing in A1 servo on the very outer focus points. It seems to drag & hunt whereas the 7d locked straight away.
Hoping it is something simple. All help greatly appreciated.

Kind regards, Kevin.

Try first to use the cross type points only, to see if that improves things.

apersson850 wrote in post #16983019
Try first to use the cross type points only, to see if that improves things.

Hi there, Yes, have tried these. The outer ones are cross type. Problem is persisting

The 5D3 AF system is more complex than my ex wife.

http://cpn.canon-europe.com …_AF_setting_gui​debook.pdf

That's the user guide for the AF system and it'll tell you what AF points are active with what lenses and widest apertures.

Apparently 21 cross type AF points can be used with that lens and other f/5.6 lenses.

For the lens that you are using, only the central 21 points are cross type:

rrblint wrote in post #16983513
For the lens that you are using, only the central 21 points are cross type:

Hosted photo: posted by rrblint in
./showthread.php?p=169​83513&i=i162025891
forum: Canon Digital Cameras

Thank you for that. Greatly appreciated. What I can't understand though is that it was perfect on the 7D but hunts on the 5D3. Were all the 19 points on the 7D Cross type with this lens?

Frosticles wrote in post #16983591
Thank you for that. Greatly appreciated. What I can't understand though is that it was perfect on the 7D but hunts on the 5D3. Were all the 19 points on the 7D Cross type with this lens?

According to the 7D manual no, provided that the lens is racked out far enough so that the maximum aperture becomes f5.6. I suspect though that it's not a hard cut-off when the lens hits f5.6 and that the cross-type points may continue to work for some focal lengths even after the lens reaches f5.6(just guessing here though).

It's only the outer ones that are hunting. All the others seem to be fine