Louis-Jacques-Mandé Daguerre was born on the 18th of November 1787 and died on the 19th of July 1851.
In 1829, Daguerre partnered with Nicéphore Niépce, an inventor who had produced the world’s first heliograph in 1822 and the first permanent camera photograph four years later. Niépce died in 1833, but Daguerre continued experimenting and evolved the process which would subsequently be known as the Daguerreotype.
Earliest surviving heliographic engraving. The plate was exposed under an ordinary engraving and copied it by photographic means. This was a step towards the first permanent photograph from nature, taken with a camera obscura, in 1826.
After efforts to interest private investors proved fruitless, Daguerre went public with his invention in 1839. At a meeting of the French Academy of Sciences on 7 January of that year, the invention was announced and described in general terms, but all specific details were withheld. Members of the Academy and other select individuals were allowed to examine specimens at Daguerre’s studio. The images were enthusiastically praised as nearly miraculous and news of the Daguerreotype quickly spread. Arrangements were made for Daguerre’s rights to be acquired by the French Government in exchange for lifetime pensions for himself and Niépce’s son Isidore; then, on 19 August 1839, the French Government presented the invention as a gift from France “free to the world” and complete working instructions were published.
In 1826, prior to his association with Daguerre, Niépce used a coating of bitumen to make the first permanent camera photograph. The bitumen was hardened where it was exposed to light and the unhardened portion was then removed with a solvent. A camera exposure lasting for hours or days was required. Niépce and Daguerre later refined this process, but unacceptably long exposures were still needed.
After the death of Niépce in 1833, Daguerre concentrated his attention on the light-sensitive properties of silver salts, which had previously been demonstrated by Johann Heinrich Schultz and others. For the process which was eventually named the Daguerreotype, he exposed a thin silver-plated copper sheet to the vapor given off by iodine crystals, producing a coating of light-sensitive silver iodide on the surface. The plate was then exposed in the camera. Initially, this process, too, required a very long exposure to produce a distinct image, but Daguerre made the crucial discovery that an invisibly faint “latent” image created by a much shorter exposure could be chemically “developed” into a visible image. The latent image on a Daguerreotype plate was developed by subjecting it to the vapor given off by mercury heated to 75° Celsius. The resulting visible image was then “fixed” (made insensitive to further exposure to light) by removing the unaffected silver iodide with concentrated and heated salt water. Later, a solution of the more effective “hypo” (hyposulphite of soda, now known as sodium thiosulfate) was used instead.
The resultant plate produced an exact reproduction of the scene. The image was laterally reversed — as images in mirrors are — unless a mirror or inverting prism was used during exposure to flip the image. To be seen optimally, the image had to be lit at a certain angle and viewed so that the smooth parts of its mirror-like surface, which represented the darkest parts of the image, reflected something dark or dimly lit. The surface was subject to tarnishing by prolonged exposure to the air and was so soft that it could be marred by the slightest friction, so a Daguerreotype was almost always sealed under glass before being framed (as was commonly done in France) or mounted in a small folding case (as was normal in the UK and US).
The Daguerreotype was the Polaroid film of its day: it produced a unique image which could only be duplicated by using a camera to photograph the original. Despite this drawback, millions of Daguerreotypes were produced. The paper-based calotype process, introduced by Henry Fox Talbot in 1841, allowed the production of an unlimited number of copies by simple contact printing, but it had its own shortcomings—the grain of the paper was obtrusively visible in the image and the extremely fine detail of which the Daguerreotype was capable was not possible. The introduction of the wet collodion process in the early 1850s provided the basis for a negative-positive print-making process not subject to these limitations, although it, like the Daguerreotype, was initially used to produce one-of-a-kind images—ambrotypes on glass and tintypes on black-lacquered iron sheets—rather than prints on paper. These new types of images were much less expensive than Daguerreotypes and they were easier to view. By 1860 few photographers were still using Daguerre’s process.
The same small ornate cases commonly used to house Daguerreotypes were also used for images produced by the later and very different ambrotype and tintype processes, and the images originally in them were sometimes later discarded so that they could be used to display photographic paper prints. It is now a very common error for any image in such a case to be described as “a Daguerreotype”. A true Daguerreotype is always an image on a highly polished silver surface, usually under protective glass. If it is viewed while a brightly lit sheet of white paper is held so as to be seen reflected in its mirror-like metal surface, the Daguerreotype image will appear as a relatively faint negative—its dark and light areas reversed—instead of a normal positive. Other types of photographic images are almost never on polished metal and do not exhibit this peculiar characteristic of appearing positive or negative depending on the lighting and reflections.
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