Autofocus Question

[RobertG]

I am trying to come to terms with the manner in which the G1 autofocuses.

I understand you need contrast, which implies sufficient light.

Does anyone know what percentage of the center (of the LCD screen or viewfinder for example) is used for the reading?
I have found that small objects dead center often get missed, and I have to manually focus to get it right (the camera wants to focus on the background)

This is not a rant. I was just wondering about the percentage :)

Has anyone tried a contrast enhancing filter (like a light yellow) to see if it improves the hit ratio for the autofocus?

(You could adjust the WB to correct for the yellow)

Thanks