AI SERVO on 1D stinks??!!!!

[jcpr]

Hi everybody:

I have a question for you photo gurus out there.

Suppose I have my 1D with a 300 2.8L mounted, all positioned in a wide wall, so that both the body and the lens are perfectly still.

I now point my gear towards a traffic sign about 21 ft or 7 meters away.

Now i set the camera to AI SERVO, Evaluative metering and HI Speed continuos shooting, center point auto focus, with the Servo Change Sensitivity to Slow and automatic AF focus expansion to 7 point TTL, using the Custom Functions.

Then i focus on the traffic sign with the center point, wait until it looks tack sharp and fire a blaze of 8 consecutive shots.

Considering it's in SERVO mode and that it's sit on a wall, shouldn't all the photos be tack sharp?

With my 1d they aren't.

Only the first is properly focused and exposed. All the following are 2/3 to 1 stop overexposed and soft focused, mostly front focused.

I had my camera in Canon's representative in Portugal for 8 ( thats right... eight ) months. They say they sent the camera to Germany, where they replaced the front panel and the main cpu or something!! The camera is exactly as i left them.

Fortunately i managed to get a cps loan of another 1d, that didn't had this focus problem ( at least not apparently ) and most definetely did not overexposed the 2nd and following photos from a Hi Speed Burst!!!

I'm prepared to ask for a new camera.

I'll post some pictures of some tests that i'm doing, just to clear all doubts.

Meanwhile, please and my question...

Considering it's in SERVO mode and that it's sit on a wall, shouldn't all the photos be tack sharp?

I'm using a remote to fire the camera.

Thanks guys

José

[gsrossano]

I use a 1D with the 300/2.8 a great deal and find the servo focus works ok, so it may be you body is a lemon.

If you are focusing using just one spot, the camera may hunt for focus if there is not much detail covering the one spot. Also try your experiment using all 45 focus spots. If the problem goes away you probably don't have enough detail covering one spot. or are moving the camera slightly as you take the frames. Without seeing the shots I'm just guessing of course.

Anyway, try your test on a tripod. Use a target with plenty of detail in one focus spot and all 45 focus spots. Compare the results using one spot and all 45. If you still have problems something is wrong with the body.

As for the exposure shift, that shouldn't be either if the target does not move around on the light sensor. I have not seen that with my 1D.