Short exposure images recorded during an open-loop test of F&F. Individual images consist of 10 aligned and stacked images, each with an integration time of 19 μs, with a total integration of 0.19 ms. These show that the PSFs are severely distorted by the challenging atmospheric conditions. The first Airy ring is always broken up, and higher order diffraction structure is not visible. All PSFs are normalized to their maximum value, and are plotted in logarithmic scale.