The point spread function (PSF) for a ground–based telescope is calculated for two types of wave–front correctors, i.e., deformable and segmented mirrors. The deformable mirror is assumed to be a thin square plate fixed at its center and deformed with a system of lateral forces applied to 20 points. The segmented corrector is a set of square segments with three degrees of freedom, the number of elements varies from 1 to 16. The wave–front distortions are of the Kolmogorov spectrum and are considered to be known for each random realization. It is shown that the PSF calculated for a 9–element segmented corrector (27 degrees of freedom) is close to that obtained for the deformable mirror with 27 degrees of freedom.