1D Mark II N - AF help

I thought I'd post the Q here as i'm looking for some help on the 1D Mark II N autofocus parameters.

I've been shooting birds in flight with lots of OOF head and sharp bodies and could really do with some tips on using CF 13 (no of AF), 17 (AF activation area) and 20 (AIServo sensitivity). The AF locks on ok, but I get peripheral rather than central AF shift when in AIServo.

I've read the manual but would like to know the sort of settings and their applications that sport photogs use.

Thanks in advance.

Welcome John. Are you using 45-point auto focus point selection for these shots?

Nill
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www.toulme.net

Yes I was, I've since spent Sunday morning shooting motocross and started to use single and pairs of AF points at selected parts of the frame, together with spot metering. What an improvement. much faster AF and tack sharp on the EF 70-200 f2.8.

Hi John,
I've tried those functions and haven't noted a hugh difference in performance. But I'm not a dedicated sports/action shooter. So you have to take my experience with a grain of salt. I think these are my settings.

13. Number of AF points / Spot metering: 1 - 11 / Active AF point
I want my AF point to be where I meter.

17. AF point activation area: 2 - Automatic expand (max 13 AF points)
I think this is what I picked for sports as I mainly shoot the center AF.
I really haven't noted a hugh difference between the settings though.

20. AI servo tracking sensitivity: 0 - Standard
I've experimented with the settings, but I'm not sure I noticed anything really noticable.

Well, sport is one thing, and birds in flight are, well, birds of a different feather. In fact, the latter is about the *only* situation that I use 45-point AFPS for. For almost all sport, I use center point, CF4-3, CF17, 20 and 21 all at default settings, and of course AI servo. I experimented with the other CF17 settings and found that they resulted, in general, in more OOF frames. CF-13 has no real application to the AF question as all it does is limit the number of AF points that are available for *manual* selection. (It also lets you link spot metering to the active AF point, but that's not what you're asking about.)

For birds in flight, I (and presumably the camera) have enough trouble just keeping the AF point on the bird, much less capturing the eye rather than the wing. Assuming that you don't have a real back focus problem (which is possible but doesn't sound very likely given what you've said), it may be that it's simply a matter of needing to stop down a bit and going for a little more DOF.

Having said that, I have to add that you'll almost certainly get some more educated responses on the bird side over in the wildlife form.

Nill
~~
www.toulme.net

Nill's right again

Birds in flight will test the best of us. They are unpredictable, except flocks of geese in the fall. Coming in for a landing they will shift left/right in a blink or suddenly veer off or come straight at you. Hawks and other raptors are tough when they stoop for the kill. Small songbirds in flight have been known to put photographers in mental institutions.

I use CPF, AI Servo and all the IS I can buy. The real secret is to pan and tilt smoothly to maintain the same focus point. Pure practice is the only real answer. I used to spend hours at a local park that had a carousel (merry-go-round). Pick a spot thats coming at you and try to stay on it, taint easy my friend.
The local motocross track is another good practice place. Catch them coming over a jump where you CAN"T see their approach - surprise, The Apex shot is good but the downfall angles happen fast also. Just keep working at it and find the cameras best settings.