Figure 9: The kurtosis of the ADU statistics on three images taken with WiFSIP during precommissioning on Robotel, at the Astrophysical Institute in Potsdam. All three quadrants of the imaging CCD with bright stars in them show a peaking kurtosis close to the best focus position. The one flat line is the kurtosis in quadrant 1, which was essentially free of stars. The small inserts on top are tiny windows around two bright stars in the field at the different focus positions.