In a device for converting into video signals the light signals from desired sections of a flat object such as a slide or a photographic print using a CCD-sensor (32), an optical system is provided which includes a lens unit (35) with a constant focal length. The optical system comprises at least two...http://www.google.fr/patents/US5276534?utm_source=gb-gplus-shareBrevet US5276534 - Optical apparatus for maintaining a focussed image by interconnected adjustment of object and image distances
Optical apparatus for maintaining a focussed image by interconnected ...
