Shooting a sporting event.

I took my K20d and my 6 year old Tamron 28-200 and this being the first time I tried to shot something moving fast. Most of the shots came out OK. The problem I had been when I moved the camera to stay with the person on the BMX some of the shots did not focus 100 %. If I was in a fixed spot and shot the person on the bike coming at me as he or she went around no problem. But If I started to swing the camera around to get the next shot my K20 had a hard time with it. I tried both Green and Programmed mode had the same problem. Anything I can do to fix the problem of a quick focus on an object that is moving? Better Lens or change something on the camera. Or just more time doing sport photography?

Are you using continuous or single focus?
Pentaxes dont have a good track record when it comes to focusing continuously.
I've tried AF-C while shooting seagulls with no success.
If I miss focus I just turn the focus ring closer to the proper focus point and then AF again.

This wont help track moving objects very well though.

Here are some of my sport shots link

The thing is not to focus, they are moving too fast so pre-focus on the spot were you want to make a photo. Aim ahead of that point and track the subject and when they are in the focus spot *click* and you should have it.

I had is on AF-S.
Thanks for the tip Anvh, will try that next time.

Don't forget that there is a small lag between you thinking that you want to release the shutter, actually pressing the button and then the camera firing.

This means you shoot just before the precise moment you want to make the exposure.