Mackenstein  autochrome viewer: “Le Pantochrome”
                        
                Mackenstein autochrome viewer: "Le Pantochrome". Also appears in Mattey's catalogue: Described as a monocular viewer having a focusing biconvex lens and 45° ground glass screen giving high luminosity to autochromes placed in a slide changer for portrait and landscape views. See original attached document.            
            
                
                
                	MarqueMackenstein  Visionneuse autochrome
 	             
            	
	            	MarqueMackenstein  Visionneuse autochrome