I have the F2 has my starter MD.
If i recall (from last summer) you need to hold the pinpoint button with the coil on the ground for a few seconds to ground balance then it will be good to go.
Personally, i have rarely used the pinpoint function on the F2 since it was so accurate during the sweeps. I just did an X pattern sweep, sweep left to right, turn myself 90 degrees then do it again. 90% of the time with my standard 8 inch coil the target is in the middle of the center coil (where it goes beep). I take my screwdriver and poke it in the middle of the opening of the coil to mark it.
side note: My unit broke down after a year and i kept getting constant chatter like a machine gun with the numbers jumping all over the place. I called fisher and RMA'd it and received a new head unit and coil within a week.