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.
Mackenstein Visionneuse autochrome