A new effective method of the point-spread-function (PSF) evaluation of reflection focusing systems in the proximity of its geometrical focus is proposed. This method is based on the imaging in this reflection system a spherical ball reflector with its center positioned near system focus. It was shown, that imaging of this ball (using the same scanning system as for object imaging, i.e. C-scan) allows to directly obtain spatial distribution of the PSF of the focusing system. Results of the experimental evaluation of the PSF of the factory-made acoustic lenses at frequencies up to 1.2 GHz as well as laboratory made focusing system are given.