EOS10D AI FOCUS PROBLEM

[speedbird15]

[[color=darkred]
I've encountered a problem with my brand new Eos10d : in AIservo mode one out of three photographs are out of focus. My main subjects are flying aircrafts, and with my old Eos3 I've never had similar problems.
I use a Canon 100-300 F5,6 USM. My other lens, a Sigma 400 f5,6 HSM, gives an error99 code after one or two shots. Is this an incompatibility problem ? Can it be solved ? Updating the firmware can be a solution ?
Thank You for Your help.

[KennyG]

The 10D's AI Servo mode takes time to grab focus and you will usually find if you take the shot within the first one to one and a half seconds it stands a pretty good chance of being OOF. If you take a sequence of shots you may find the first OOF and the rest OK. Just learn to start getting focus earlier or not be so keen on taking the shot before AI Servo has chance to do its thing.

You may be able to have your Sigma lens upgraded but you should check with Sigma as not all older lenses are suitable.

[robertwgross]

Was the 10D strictly handheld, or were you using some kind of tripod or support?

Was the aircraft color high in contrast, like most are? If its color was close enough to the sky, then the autofocus system is struggling to figure out what the real subject is.

I find that if I am (stupidly) trying to handhold a long lens for a far-away subject, I am typically bouncing around enough so that the focus point is hitting on and off the true subject. Obviously, that gets me poor results.

Like Kenny said, shoot off a burst and maybe some of them will be fully in focus, even if the first one isn't.

On the Sigma lens, some of them can be updated by Sigma. I suggest you contact them before you try to send it in.

---Bob Gross---