Abstract: Substrates, such as spectacle lenses for example, may be provided with a coating which is not uniform by way of screens. The screens are aperture rings, arranged concentric to a symmetry axis of the vaporising crucible in a vacuum coating unit, by way of a screen holder. The spectacle lenses are disposed on a substrate holder also in circles about the symmetry axis. The shadows cast by the aperture rings cover but a partial region of the spectacles lenses such that those regions of the lenses receive less coating than in the unshaded free regions. The aperture rings are exchangeable in order to match the coating process to the customer requirements. Furthermore, the separation of the subtrate holder from the aperture rings is adjustable.