A zone focusing lens system is provided for use as a photographic camera objective. In the system, a fixed positive meniscus is placed ahead of the system aperture stop and is provided with an aspheric surface that is structured primarily to correct for off-axis aberrations. A lens disk having a plurality...http://www.google.fr/patents/US4443067?utm_source=gb-gplus-shareBrevet US4443067 - Zone focusing optical system
