The best way to prevent the focus from being "distracted" is to use a single point. Of course, that makes for much more work for you, keeping that AF point right on the subject, exactly where you want the camera and lens to focus.
Later camera models than 40D have more choice of focus patterns, such as Zone and Expansion.... which can be useful with BIF. Some models' AF you also can "tune" to help prevent them beting "distracted" by obstructions or things at a distance behind the subject.
Also the cameras with more AF points (80D, 77D, T7i and 6DII have 45 points... recent 5D-series and 1D-series models have 61 points.... 7D Mark II have 65 points). With more points, there's less "gap" between individual points, which makes some of the multi-point patterns more usable for subjects like BIF. (But I never use All Points/Auto... way too big coverage, too easily distracted, and once that happens focus may hunt for a while before it again finds the subject)
Depending on model, newer AF systems also may be color and movement sensitive, which can help when tracking fast moving subjects.
If I recall correctly, the 40D's AF system was very nicely improved over the 30D's (which I used a lot... I only used 40D a few times, but eventually used 50D w/same AF system a lot). But, there have been further, significant advancements since, especially noticeable with the latest DSLRs. Many are now able to focus in 2 or 3 EV lower light and even with teleconverter/lens combos that are effective f/8.
I use the 100-400mm II myself. It's fast, though not quitre as quick as some other lenses. As an f/4.5-5.6 lens, it just doesn't provide as much light for the AF sensors to work with.... an f/2.8 zoom or f/2, f/1.8 or f/1.4 prime can be faster . Still, on my 7DIIs the 100-400 II is plenty fast for most things.
BIF are particularly challenging, though. Any camera and lens might struggle with them due to their speed, rapid changes in direction, etc. I think it's fair to say all shooters have some missed focus shots with BIF, regardless how capable their gear might be. OTOH, sometimes we just get lucky! Following was done with a 5D Mark II (which has a pretty pokey AF system, nowhere near as quick or good trackng movement as 50D, 7D, etc., in my experience):
Lens was Canon's EF 300mm f/4L IS USM, which I've used a lot handheld when shooting sports. I had a whole bunch of missed focus and poorly composed shots of that hawk, trying to shoot it with the 5DII. But the bird was cooperative and kept zooming past, circling and hunting right around me for about 45 minutes.... and the 5DII was the camera I had on hand, so it was what I used. (I brought the full frame to take some scenic shots, wasn't expecting to shoot BIF! I know I could have done better with my 50Ds, which were what I was using along with the full frame camera at the time.)
I use pretty much the same settings as you, except I never use All Points. When I had cameras which only offered Single Point as an alternative, that was what I used. Now with other cameras I sometimes use Zone or Expansion, but still generally avoid All Points. That just leaves too much up to chance, for my liking.
Finally, I have to say, autofocus with these cameras and lenses is faster and more accurate than I ever was shooting with manual focus gear.... And I was actually quite good, shooting sports with my film cameras "back in the day".
It''s probably the limitations of your camera's AF system.... unlikely the lens which is a very good performer in reasonably good lighting conditions (I switch to f/4 or faster lenses in more challenging light). Practice will help too, I'm sure (and perhaps some patience). Try Single Point, but expect to need to do more work with it. If and when you upgrade to a new camera you'll very likely be getting a higher performance AF system in it, which will bring out the best of that lens.
***********
Alan Myers
San Jose, Calif., USA
"Walk softly and carry a big lens."
GEAR: 5DII, 7DII (x2), 7D(x2) some other cameras, various lenses & accessories
FLICKR & ZENFOLIO
Thank you for your informative reply amfoto1.
Thank you to the others that replied as well.
My concern about the lens possibly being part of the focus issue has been alleviated.
I discovered yesterday that I simply have to lessen the lens focal length to reacquire focus much quicker than what had been happening.
Probably similar to what is suggested in Waddizzle's post.
Regarding using a single AF point for BIF, the common technique from what I've read is to use the centre AF point only.
My understanding for this is that the centre AF point is more accurate / better focus, at least for the Canon 40D.
I've tried this and haven't had a lot of success and I need to practice it more.
Unfortunately, my time for BIF photography is very limited for the most part.
So, I use all AF points being active to increase my chances of getting some in focus shots.
I only use all AF points when the bird is an open sky setting..usually a clear blue sky.. with nothing to pull focus off the bird.
If the bird is flying among trees or buildings, then I use the centre AF point only, with little success.
I know I would have zero chance of getting a flying small bird in focus just using the centre AF point.
Other than more practice, the other thing that I hope will help me, is a newer camera with an updated focus system.
I'm hoping that the rumored Canon 7D Mark III does get released sometime between now and next Spring.
Thought about getting the current Mark II but, I can wait until next Spring to see if there is going to be a Mark III.
This Osprey picture was taken recently using all AF points active.
Other than cropping, there were very little Lightroom adjustments to this image if i remember correctly. It's almost "straight out of the camera".
Not sure how this will appear regarding size and resolution on this site but, it looks good on my desktop screen.
Osprey, eagles and hawks are my main BIF attempts.
Again, thanks for all the replies.
"What difference does it make if Lightroom does the lens correction as a preset or if the correction is done in the develope mode?"
Do you mean, as a preset or as if you do it in the Develop Module? If I understand you correctly, it makes no difference. It is just easier to do it as a preset because it should be done to every photo. Doesn't matter that it is a BIF.
I am a big believer in post editing because that is where great photos are made. Lens correction is just one that all photos should have done to them.
" I would like to get closer to the birds ..."
Although, this is the best advice, you have to work with what you have. Perhaps a change in technique would help in getting closer. Good photographers always adapt and change. That is just part of the game.
