Strange AF behavior on my 1D Mk.IIN, please HELP!

[Igor]

Still can't figure out if my new 1D-IIN has focus problems...
Two shots below should illustrate the problem.

I focused on the tit, the red rectangle shows the approximate position of the central AF point. Shot a short burst, the tit on all frames is out of focus, but the twig behind the bird is in focus.

In a second tit flipped across and I shot another burst. On all shots the tit is in focus, but the central point was not on a bird, but in on the front twig (see red rectangle).

So, do I have a back focus, or my AF setting are wrong?
They are: AF-SERVO, central point AF plus auto expansion to 13 points at 200mm and more.
1/2000, f/6.3, ISO400, 100-400L lens.

Please help.
Thanks.

First burst, downsized full frame:
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http://i62.photobucket.com/albums/h90/nikkorer/ff-1DN_0384-RS.jpg

First burst, 1:1 crop:
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http://i62.photobucket.com/albums/h90/nikkorer/11-1DN_0384-RS.jpg

Second burst, downsized full frame:
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http://i62.photobucket.com/albums/h90/nikkorer/ff-1DN_0389-RS.jpg

Second burst, 1:1 crop:
-------------------------------
http://i62.photobucket.com/albums/h90/nikkorer/11-1DN_0389-RS.jpg

[Keith]

My recommendation is get rid of the 13 point, for shooting small birdies I have had little success. When shooting long distances the dof is shallow and wiht 13 point you cant control which point is giving you focus tracking. I would move to 7 point only for small birdies in flight when there is a distracting background that may try to pull the focus off the bird, secondly 90% of the time I am on single point on 45af and I move it around to where I want the focus point to frame the bird. I personally think you might have more success trying this Igor. Secondly AI servo only for BIF's unless on tripod where you can guarantee no movement this way :) Just my two pennies worth.

Let me know how you make out...........

If that doesnt work, will send you some charts to shoot and we can get a good idea if backfocusing might be an issue. For me moving to the 1dmkIIn was a good upgrade in AF for Bif's, as far as stationary I saw no difference

[Jeff JTPhoto]

I agree with Keith Igor. 13 point expansion is probably giving you too much of an AF area. Like Keith I prefer 7 point expansion or Center Point only. Also fo A1 Servo check that AF sensitivity (C.Fn.-20) is set to moderate not fast. This does not affect how fast the AF works, but only how it is affected by objects moving through the frame. I find that for A1 Servo I also like to have the focus controled by the * button (C.Fn.-04) rather then the shutter button. This method then provides focus lock when the * button is released while still allowing the 1/2 shutter press to change exposure when in Av, Tv, & P modes

[Igor]

BIG thanks guys, will try the new settings tomorrow and LYK.