The daguerreotype (original French: daguerréotype) is an early type of photograph, developed by Louis Daguerre, in which the image is exposed directly onto a mirror-polished surface of silver bearing a coating of silver halide particles deposited by iodine vapor. In later developments bromine and chlorine vapors were also used, resulting in shorter exposure times. The daguerreotype is a negative image, but the mirrored surface of the metal plate reflects the image and makes it appear positive in the proper light. Thus, daguerreotype is a direct photographic process without the capacity for duplication.
While the daguerreotype was not the first photographic process to be invented, earlier processes required hours for successful exposure, which made daguerreotype the first commercially viable photographic process and the first to permanently record and fix an image with exposure time compatible with portrait photography.
The daguerreotype is named after one of its inventors, French artist and chemist Louis J.M. Daguerre, who announced its perfection in 1839 after years of research and collaboration with Joseph Nicéphore Niépce, applying and extending a discovery by Johann Heinrich Schultz (1724): a silver and chalk mixture darkens when exposed to light. The French Academy of Sciences announced the daguerreotype process on January 9 of that year. The announcement of the daguerreotype process in 1839, along with William Fox Talbot's in the same year, marks the date used as the invention of photography.
Instead of Daguerre obtaining a French patent, the French government provided a pension for him . In Britain, Miles Berry, acting on Daguerre's behalf, obtained a patent for the daguerreotype process on 14 August 1839. Almost simultaneously, on 19 August 1839, the French government announced the invention a gift "Free to the World".
The mercury vapour condensed on those places where the exposure light was most intense, in proportion with the areas of highest density in the image. This produced a picture in an amalgam, the mercury vapour attaching itself to the altered silver iodide. Removal of the mercury image by heat validates this chemistry. The developing box was constructed to allow inspection of the image through a yellow glass window while it was being developed.
The next operation was to "fix" the photographic image permanently on the plate by dipping in a solution of hyposulphite of soda – known as "fixer" or "hypo". The image produced by this method is so delicate it will not bear the slightest handling. Practically all daguerreotypes are protected from accidental damage by a glass-fronted case. It was discovered by experiment that treating the plate with heated gold chloride both tones and strengthens the image, although it remains quite delicate and requires a well-sealed case to protect against touch as well as oxidation of the fine silver deposits forming the blacks in the image. The best-preserved daguerreotypes dating from the nineteenth century are sealed in robust glass cases evacuated of air and filled with a chemically inert gas, typically nitrogen.
In the early 1840s, the invention was introduced in a period of months to practitioners in the United States by Samuel Morse, inventor of the telegraph code. One of these original Morse Daguerreotype cameras is currently on display at the National Museum of American History, a branch of the Smithsonian, in Washington, DC. A flourishing market in portraiture sprang up, predominantly the work of itinerant practitioners who traveled from town to town. For the first time in history, people could obtain an exact likeness of themselves or their loved ones for a modest cost, making portrait photographs extremely popular with those of modest means. Their wealthy counterparts continued to commission painted portraits by fine artists, considering the new photographic portraits inferior in much the same way their ancestors had viewed printed books as inferior to hand-scribed books centuries earlier. In some ways they were right, in other ways wrong; the vast bulk of 19th-century portrait photography effected by itinerant practitioners was of inferior artistic quality, yet the work of many portrait painters was of equally dubious artistic merit, and although photographic images were monochrome, they offered a technical likeness of the sitter no portrait painter could achieve. The first erotic photography and the first experimenters in stereo photography also utilized daguerreotypes.
This method spread to other parts of the world as well. In 1857, Ichiki Shirō created the first known Japanese photograph, a portrait of his daimyo Shimazu Nariakira. This photograph was designated an "Important Cultural Property" by the government of Japan.
The daguerreotype is commonly, erroneously, believed to have been the dominant photographic process into the late part of the 19th century in Europe. Evidence from the period proves it was only in widespread use for approximately a decade before being superseded by other processes:
Daguerreotype cameras are expensive. In May 2007, an anonymous buyer paid 588,613 euros (792,000 USD) for an original 1839 camera made by Susse Frères (Susse brothers), Paris, at an auction in Vienna, Austria, making it the world's oldest and most expensive commercial photographic apparatus.
The Daguerreotype's popularity was not threatened until photography was used to make imitation Daguerreotypes on glass positives called "ambrotypes."-Meaning "imperishable picture" named by "Marcus A. Root.(Newhall, 107)
Daguerreotypy continues to be practiced by enthusiastic photographers to this day, although in much smaller numbers; there are thought to be fewer than 100 worldwide. Its appeal lies in the "magic mirror" effect of light reflected from the polished silver plate through the perfectly sharp silver image and in the sense of achievement derived from the dedication and hand-crafting required to make a daguerreotype.