Auto Focus Points For BIF

Hello
I've been trying my luck recently for BIF photography and I have a question regarding auto focus points.

The last couple of times out, it's been clear blue skies and I figured having all the focus points active in AI Servo mode would increase my chances of getting an in focus shot.
There is nothing in the sky other than the bird so, there shouldn't be anything to pull the focus away from the bird.

Is having all the auto focus points active a good technique to use in this situation?

Or, should I be using centre point only and try my best to keep the centre point on the head area?

For the most part, a few of the focus points have been on the bird and I've gotten for me, what I consider, some half decent pictures considering the focal length of the lens being used. 70-200 f4 non IS on a 40D

The bird I've been shooting is an adult osprey and it's flown fairly close to me at times but, I can't quite get the eyes in as sharp focus as I would like.
I don't know if that's due to my technique/settings or the focal length limitation of the lens being used or, the combination of both.
The bird's head is generally well lit so I don't think lighting is an issue.

I'm gradually getting a base line for settings for this particular clear blue sky situation.
ISO: 500
SS: Varies between 1600-800
Av:7.1
FL:200mm for all pictures
Shoot in manual mode using BBF and high-speed continuous shooting.

In the conditions you specify, yes all AF points works very well.

The all AF point technique falls apart when there are other things to trip it up, forground or background objects, trees etc..

If you have a subject that is filling the frame more, like a large Osprey,. then you may in fact have to try to use center AF point. You can add in "expansion" and still get center on the eye. But with 200mm, I doubt your filling the frame much?

Also, you can stop down to get more of the bird in focus,.f/8 instead of f/4 etc..

OK, that's good to know that I'm at least using a good focus technique for the situation.

You're right about not filling the frame much with the bird.
Every now and then it has come close to me but not as often as I would like.
Most of the pictures of it require a lot of cropping.

I'm getting some of what I consider to be the better pictures printed so, I'm curious as to how they turn out regarding eye sharpness.

At 200mm, I would use fewer, tighter grouped AF points. Depends on your camera of course.

Very best,

The thing is though, and this is important, you have to lock with the center point first, before it will hand off to other points. When you get to later bodies you can actually lock with other points, I think its using zone focusing.