Left panels: illumination of the image of the aperture in the Lyot stop plane of the coronagraph, with corresponding PSFs (right panels) for unit point sources originating from the corona at 48, 72, and 96 arcsec from the solar limb, or 1008, 1032, and 1056 arcsec from the solar centre. The image in this plane is inverted with respect to the pupil of Fig. 1 and the wave begins to be altered by the propagation through the coronagraph. The PSF degrades faster in the radial direction than in the transverse direction (see Fig. 3 for numerical values).