1D MkllN back button focus problem

[magirus]

Hi there. I just bought a 1D MkllN, great nick, low actuations. and am in the process of setting it up. I've set C Fn 4 - 1:AE lock/AF, for back button focus. If I focus with the back button,the camera seems to lock up for @ 10-15 seconds. I can take the shot, but the green focus confirmation light in the viewfinder remains lit and I can't refocus for the duration of this period. I can also hear what I take is the IS trying to work in this 10-15 sec period, as when I turn off IS the problem persists but there is no noise from the lens. Also the review image doesn't appear until the green focus confirm light clears and the buttons adjacent to the screen are inoperable. I've tried my 24-105L and 70-200 2.8 IS USM on the body and the result is the same. I also tested them on my 50D and they work fine there. If I re-set to C Fn 4 0, ie both functions on the shutter button everything works flawlessly. I tried clearing and resetting all custom functions to no avail. The problem seems to be with the AE lock button when C Fn 4 -1 is applied, and affects both buttons in either landscape or portrait orientation, the shutter does it's part of BBF perfectly. Have I inadvertently set some other function that is conflicting or have I got a real defect on the camera? All advice glady received.:shrug:

EDIT. When the back button is set to lock exposure it does so, but again stays locked for 10-15 secs.

 

[Chas]

I use bbaf on my id iin but not using the ae button but the focus point button to the left of it.
My settings are: C.Fn 04-1, C.Fn 18-1, C.Fn 19-0
Not had it long but seems to work ok.
Hope this helps.

 

[magirus]

I use bbaf on my id iin but not using the ae button but the focus point button to the left of it.
My settings are: C.Fn 04-1, C.Fn 18-1, C.Fn 19-0
Not had it long but seems to work ok.
Hope this helps.

Hey Chas, that worked a treat! The exposure lock button still doesn't work right, but I don't need it now anyway as the shutter button does the job. Thank you indeed Sir!