Originally posted by Qwntm
Any suggestions? Or is this just not something the Pentax's do?
As Steve was hinting, that's about the toughest auto focus situation in the playbook, for any photographer, with any camera.
A sports pro will be shooting athletes with focal lengths of 300mm or more - the subjects are actually some distance away.
I've shot cyclists moving at me faster than 50kmh, but at 200mm or more. Once they fill the frame, I stop shooting as the small DoF makes any subsequent shots unusable.
One thing you can do without purchasing anything else is to pre-focus on the area where you get the dream shot of Chloe returning to you (the grass is fine) and fire away at the K-3's high framerate after calling her.
You have an advantage over the old film togs who did this around a tennis baseline or basketball ring in that you can trade off ISO for depth of field if you like.