Backfocusing issues

Have shot a couple of D2 football games recently, and having ongoing issues with backfocusing.

So my question from those in the know is what causes that?

Is it generally related to lens or camera?

Or is it possibly "operator error"?

Last year was my first year shooting football. Didn't have these problems. Only 2 things that changed are (1) shooting in servo mode instead of one shot (2) bought a used Canon 70-200 2.8 L (used a Sigma 70-200 2.8 last year).

Still using the same 40D as last year.

Will probably take a 20D with the Canon lens out to practice one day this week and see how they turn out. Will also take the 40D with the Sigma lens. Shoot some pics with each on both Servo and One Shot and compare them.

Anyway, would appreciate any insight or knowledge on this issue.

Thanks!

D2, it can be related to both or either the camera or the lens. If you have two bodies, try the lens on each camera and see if the results are the same.. if so its the lens.

If not, take the effected body and try other lenses on it, if the problem persists.. then its the body.

Now the solution, I'm not sure if the 40D had the micro-adjustment feature or if that started with the 50d? If it doesnt you can always send the lens and the body to canon to have them calibrated to match each other, this gives optimal results.

It really shouldnt have anything to do with using AI servo, which is what you should be using most of the time for sports anyway.

The 40D doesn't have microadjustment. My advice would be to test you lens. Here's the link describing the test. The sheet to download is toward the bottom of the sheet.

D2. Can you post some example shots?

Pretty sure I dumped the ones that weren't usable.

Am planning to use the info from Asysin2leads tonite to see if any headway there.

But regardless, am headed from Georgia to Arkadelphia, Arkansas this weekend for a game. Haven't had a chance to try out the various camera/lens combos at practice as I wanted to do (been raining every day).

So just gonna carry the Sigma lens rather than the Canon. I'll have a 20D with me, and if I see problems when I review pictures, I'll change bodies (meaning neither of the common components that have been using will be in use) and keep shooting.

Will see how those turn out.

My 40D was backfocusing with moving subjects. Static test shots were fine. The predictive autofocus was having difficulty keeping up with movement, especially sprints during track season. I sent it to Canon twice and it got a bit better the second time but not perfect. The one thing I did to help out was switch to an off-center focus point and put that point on the runner's head. Since fast runners are leaning forward a bit that put the majority of the body in focus.

ChunkyDA wrote in post #8669097
My 40D was backfocusing with moving subjects. Static test shots were fine. The predictive autofocus was having difficulty keeping up with movement, especially sprints during track season. I sent it to Canon twice and it got a bit better the second time but not perfect. The one thing I did to help out was switch to an off-center focus point and put that point on the runner's head. Since fast runners are leaning forward a bit that put the majority of the body in focus.

Another problem with runner can be their arms pumping in front of their chests. The AF can occasionally catch the arms and it can really throw the AF off.

DDCSD wrote in post #8669405
Another problem with runner can be their arms pumping in front of their chests. The AF can occasionally catch the arms and it can really throw the AF off.

I found this to be true of the MkIIn and the MkII over my 40D. Tries to log on to more things. It takes a bit of getting used to.