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Louis Daguerre's 1838
daguerreotype of a busy street, with only one man remaining in one place long enough to be clearly visible (near the bottom left corner). , probably October or November 1839, an approximately quarter plate size daguerreotype. Niépce died suddenly in 1833, leaving his notes to Daguerre. More interested in silver-based processes than Niépce had been, Daguerre experimented with photographing camera images directly onto a mirror-like silver-surfaced plate that had been fumed with
iodine vapor, which reacted with the silver to form a coating of
silver iodide. As with the bitumen process, the result appeared as a positive when it was suitably lit and viewed. Exposure times were still impractically long until Daguerre made the pivotal discovery that an invisibly slight or
"latent" image produced on such a plate by a much shorter exposure could be "developed" to full visibility by
mercury fumes. This brought the required exposure time down to a few minutes under optimum conditions. A strong hot solution of common salt served to stabilize or
fix the image by removing the remaining silver iodide. On 7 January 1839, this first complete practical photographic process was announced at a meeting of the French Academy of Sciences, and the news quickly spread. At first, all details of the process were withheld and specimens were shown only at Daguerre's studio, under his close supervision, to Academy members and other distinguished guests. Arrangements were made for the French government to buy the rights in exchange for pensions for Niépce's son and Daguerre and to present the invention to the world (with the exception of Great Britain, where an agent for Daguerre
patented it) as a free gift. Complete instructions were made public on 19 August 1839. Known as the
daguerreotype process, it was the most common commercial process until the late 1850s when it was superseded by the
collodion process. with his family, 3 or 4 November 1839. Possibly by
Carl August von Steinheil. French-born
Hércules Florence developed his own photographic technique in 1832 or 1833 in Brazil, with some help of pharmacist Joaquim Corrêa de Mello (1816–1877). Looking for another method to copy graphic designs he captured their images on paper treated with silver nitrate as contact prints or in a camera obscura device. He did not manage to properly fix his images and abandoned the project after hearing of the Daguerreotype process in 1839 and did not properly publish any of his findings. He reportedly referred to the technique as "photographie" (in French) as early as 1833, also helped by a suggestion of De Mello. Some extant photographic contact prints are believed to have been made in circa 1833 and kept in the collection of IMS.
Henry Fox Talbot had already succeeded in creating stabilized photographic negatives on paper in 1835, but worked on perfecting his own process after reading early reports of Daguerre's invention. In early 1839, he acquired a key improvement, an effective fixer, from his friend
John Herschel, a
polymath scientist who had previously shown that hyposulfite of soda (commonly called "hypo" and now known formally as
sodium thiosulfate) would dissolve silver salts. News of this solvent also benefited Daguerre, who soon adopted it as a more efficient alternative to his original hot salt water method. In 1837, mineralist-writer
Franz von Kobell shot finely detailed salt-paper negatives of different perspectives of the
Munich Frauenkirche and other local buildings. Kobell revealed his work in 1839, together with
Carl August von Steinheil. The "Steinheil method" produced pictures with a diameter of 4 cm, and negatives were rephotographed to create positive versions. showing the American photographer
Frederick Langenheim, circa 1849. The caption on the photo calls the process "Talbotype".|257x257px Talbot's early
silver chloride "sensitive paper" experiments required camera exposures of an hour or more. In 1841, Talbot invented the
calotype process, which, like Daguerre's process, used the principle of chemical development of a faint or invisible "latent" image to reduce the exposure time to a few minutes. Paper with a coating of
silver iodide was exposed in the camera and developed into a translucent
negative image. Unlike a daguerreotype, which could only be copied by photographing it with a camera, a calotype negative could be used to make a large number of positive prints by simple
contact printing. The calotype had yet another distinction compared to other early photographic processes, in that the finished product lacked fine clarity due to its translucent paper negative. This was seen as a positive attribute for portraits because it softened the appearance of the human face. Talbot patented this process, which greatly limited its adoption, and spent many years pressing lawsuits against alleged infringers. He attempted to enforce a very broad interpretation of his patent, earning himself the ill will of photographers who were using the related glass-based processes later introduced by other inventors, but he was eventually defeated. Nonetheless, Talbot's developed-out silver halide negative process is the basic technology used by chemical film cameras today.
Hippolyte Bayard had also developed a method of photography but delayed announcing it, and so was not recognized as its inventor. In 1839,
John Herschel made the first glass negative, but his process was difficult to reproduce. Slovene
Janez Puhar invented a process for making photographs on glass in 1841; it was recognized on June 17, 1852, in Paris by the Académie National Agricole, Manufacturière et Commerciale. In 1847, Nicephore Niépce's cousin, the chemist
Niépce St. Victor, published his invention of a process for making glass plates with an
albumen emulsion; the Langenheim brothers of Philadelphia and John Whipple and William Breed Jones of Boston also invented workable negative-on-glass processes in the mid-1840s. == 1850 to 1900 ==