An unusual meter, patented by Paul Boucher of Paris, which produces a small paper negative of the subject. The front cap pulls off to reveal a large plano-convex lens, at the back of the meter is a magazine holding a stack of sensitive paper. The image produced can be viewed in subdued light, medium densities in the negative were compared to standard tints painted on the front of the paper-magazine. The closest matching tint and the time taken to reach that tint were then found in a table which gave the exposure time. Only four tints are present, the patent shows more.