Beginning in the 1880s, Léopold Mercier had a profitable business in Paris and Cabourg as a photographer and editor producing photographic reproductions of art works and publishing works such as "The History of Art in Images" (l'Histoire de l'Art en Image) by Emile Bayard. His studio was located at 27 rue de Ponthieu. To present his firm, he had small business cards in sky blue cardboard in the Second Empire style which mentioned the flattering "Medals of gold and silver, Paris 1889, Paris 1889/Photograph of the Champs-Elysées." He regularly published small advertising leaflets in which the long list of the works of painters and sculptors appearing in the studio catalogue was presented in alphabetical order. Léopold Mercier also worked in artists' studios, and covered the major art exhibitions & cultural events such as the arrival of the Buffalo Bill Circus in Paris in 1905, during which he did a magnificent series of Sioux portraits. He retired in 1913 in his Cabourg villa. The collection of his large-format glass plates was acquired by Roger-Viollet along with the agency premises located at 6, rue de Seine in 1938.