As per this photography article, Henry Talbot had invented the negative technique in 1830s. French artists also favored the paper negative and its poetic. Around 1850 the painter and experimenter Gustave Le Gray introced the waxed paper negative, which meant that the negative paper could be coated and kept up to 2 weeks before exposure…
Although immediately popular and available without patent restriction from the very beginning, the daguerrotype was not the only photographic medium announced in 1839. William Henry Fox Talbot, an amateur scientist in England had corresponding with his friend and colleague, the scientist Sir John Herschel (1792-1871), about their mutual discovering using the camera obscura and Lucida,…