Claude Félix Abel Niépce de Saint-Victor (26 July 1805, Saint-Cyr, Saône-et-Loire – 7 April 1870, Paris) was a French photographic inventor. Claude was an army lieutenant and the cousin of Nicéphore Niépce. He first experimented in 1847 with negatives made with albumen on glass, a method subsequently used by Frederick Langenheim for his and his brother’s lantern slides. At his laboratory near Paris, Saint-Victor worked on the fixation of natural photographic colour as well as the perfection of his cousin's heliographing process for photomechanical printing. His method of photomechanical printing, called heliogravure, was published in 1856 in Traité pratique de gravure héliographique. In the 1850s, he also published frequently in La Lumière.

Near-discovery of radioactivity

In the 1850s, Saint-Victor was developing color photography using light-sensitive metal salts, including uranium salts. In 1857, long before Henri Becquerel's discovery of radioactivity, Saint-Victor observed that, even in complete darkness, certain salts could expose photographic emulsions. He found that uranium salts were responsible for this anomalous phenomenon. Photographers in France, England, and Germany confirmed Niepce's findings regarding uranium. See, for example: Translation : " … this persistent activity … cannot be due to phosphorescence, for it [i.e., phosphorescence] would not last so long, according to the experiments of Mr. Edmond Becquerel; it is thus more likely that it is a radiation that is invisible to our eyes, as Mr. Léon Foucault believes, … ." Niépce mentions Edmond Becquerel, the father of Henri Becquerel, who would later be credited with the discovery of radioactivity. In 1868, Edmond Becquerel published a book, La lumière: ses causes et ses effets (Light: its causes and its effects), in which he mentioned Niépce's findings; specifically, that objects that were coated with uranium nitrate could expose photographic plates in the dark. On the controversy about whether Henri Becquerel knew about Niépce de Saint-Victor's earlier discovery of radioactivity in uranium, see: