The invention provides an apparatus for printing an image of a negative film on a photographic print paper. The apparatus is equipped with a zoom lens for changing a printing magnification rate and the zoom lens incorporates an adjustable diaphragm for changing an aperture size. A standard F-number for...http://www.google.fr/patents/US5038168?utm_source=gb-gplus-shareBrevet US5038168 - Photographic printing apparatus
