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.
Calotype
In late 1840, Talbot worked out a very different "developing-out" process (a concept pioneered by the daguerreotype process introduced in 1839), in which only an extremely faint or completely invisible latent image had to be produced in the camera, which could be done in a minute or two if the subject was in bright sunlight. The paper, shielded from further exposure to daylight, was then removed from the camera and the latent image was chemically developed into a fully visible image. This major improvement was introduced to the public as the "calotype" or "talbotype" process in 1841.