I've both of the bodies (F801 (non-s) & F601).
With my 28-85 for example, the F601 seems more rapid and hesitates less.
Maybe the F801 goes to far, then not far enough and repeats that cycle a few
times for finally find the right distance.
zzzzzzzzzzzzzzzzzzz(1)-zzzzz(2)-zz(3)-z(4)
----------------------> (1)
<------ (2)
---> (3)
<- (4)
Jean-Pierre - Belgium
