Daguerreotype
Morse met the inventor of the daguerreotype, Louis-Jacques-Mande Daguerre, in Paris in January 1839 when Daguerre's invention was announced [2]. While the daguerreotype fascinated Morse, he was concerned about how the new invention would compete with his telegraph. However, Morse's viewing of the daguerreotype alleviated his fears when he saw how revolutionary its technology was. Morse wrote a letter to his brother Sidney describing Daguerre's invention, which Sidney then published in the New-York Observer on April 20, 1839. While this was not the first report of the daguerreotype to appear in America, it was the first in-person report to appear in the United States.
Henry Collen
Calotype was an early photographic process developed by Henry Fox Talbot who was a colleague of Collen's. Talbot supplied the photographic knowledge and Collen the artistic know-how. In an article titled "Photography in the 1840s," Peter Marshall describes the distinction between daguerreotypes and calotypes. "The daguerrotype spread rapidly around the world...There were some limitations on the spread." Daguerre's process was somewhat limited by his prior patent in the UK, and so only those professionals who could afford a license were able to do so. Meanwhile, Talbot patented his calotype process in the UK and the US, but he was unable to get a patent in France which also limited its growth. Also, Marshall states, "In general, most professional photographers used the daguerreotype process in the 1840s, while the calotype was generally favored by those who were not attempting to earn an income." (A chart describing the differences between calotypes and daguerreotypes is included in the Appendix).