Daguerreotype
It is said that Daguerre has found the means to collect, on a plate prepared by him, the image produced by the camera obscura, in such a way that a portrait, a landscape, or any view, projected upon this plate by the ordinary camera obscura, leaves an imprint in light and shade there, and thus presents the most perfect of all drawings ... a preparation put over this image preserves it for an indefinite time ... the physical sciences have perhaps never presented a marvel comparable to this one.
A further clue to fixing the date of invention of the process is that when the Paris correspondent of the London periodical "The Athenaeum" reported the public announcement of the daguerreotype in 1839, he mentioned that the daguerreotypes now being produced were of considerably better quality than the ones he had seen "four years earlier".
Charles Nègre
Delaroche encouraged the use of photography as research for painting; Nègre started with the daguerreotype process before moving on to calotypes. His "Chimney-Sweeps Walking", an albumen print taken on the Quai Bourbon in 1851, may have been a staged study for a painting, but is nevertheless considered important to photographic history for its being an early instance of an interest in capturing movement and freezing it forever in one moment.