Originally posted by kunik hmmm... these are not the responses I was expecting. My understanding is that there was a specific "CIF" setting on the K20D that would somehow work different from the trap-focus you can do on pretty much any other Pentax camera (I don't know about the other manufacturer).
My understanding is the only thing new about the K20D here is that you can actually use the feature with AF lenses if they have a AF/MF switch on the lens and you have it in the MF position.
But it's not gong to magically give you a faster shutter speed than you'd get with any other method, so sharpness hardly seems a relevant difference. The only question would be how much lg time there is between when the camera notices a subject in focus and when it snaps the picture - if that's too slow, the car/bike might be gone already. That is, catch-in-focus wouldn't really improve sharpness in this scenarios - it would (ideally) help you get more pictures when the car or bike is actually visible. Sharpness would still depend on shutter speed relative to subject speed.