The charge form factor of the pion is calculated in lattice QCD. The
non-perturbatively improved Sheikholeslami-Wohlert action is used together with
the O(a) improved vector current. Other choices for the current are
examined. The form factor is extracted for pion masses from 970 MeV down to 360
MeV and for momentum transfers Q2≤2GeV2. The mean square
charge radius is extracted, compared to previous determinations and its
extrapolation to lower masses discussed.Comment: 12 pages REVTeX, 15 figures. Designation of currents clarified.
Details concerning extraction of parameters added. Version accepted by Phys.
Rev.