Moses Billings
With the development of the daguerreotype in the 1840s, the role of the portrait painter declined in general, because it was now much easier and much cheaper to have one's likeness presented in a visual format. While many portrait painters lost business in competition with the daguerreotype, Billings instead began to produce daguerreotype prints himself. It is not known exactly which prints were made by Moses Billings, as daguerreotypes were usually signed, when signed at all, along the side of the plate. Due to the traditional storing methods of daguerreotype plates, even this signature usually quickly became illegible. However, it has been generally noted, or at least hypothesized, that his daguerreotype prints showed a level of talent and artistry above that of amateur daguerreotypists. Though it is not known exactly which prints were his, it is known that he had largely abandoned the process by the 1850s. Even after he stopped making daguerreotypes, he did continue to paint people's portraits on canvas.
Louis Désiré Blanquart-Evrard
He was born and raised in Lille where he studied chemistry with Charles Frédéric Kuhlmann and miniature painting on porcelain. After Louis Daguerre solved the problem of long exposure time and introduced daguerreotypy, a practical photographic process, to the general public in 1839, Blanquart-Evrard developed interest in photography. He studied the "calotype", salt-print negative process, and in 1847 became the first person to publish on negative/positive paper photo process in France. He developed a method of bathing the paper in solutions of potassium iodide and silver nitrate rather than brushing these chemical baths on the surface. In January 1847, he presented his research on stabilizing the photo prints by floating them in the silver solution to the French Academy of Sciences.