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The daguerreotype (; (フランス語:daguerréotype)) process, or daguerreotypy, was the first publicly announced photographic process, and for nearly twenty years, it was the one most commonly used. It was invented by Louis-Jaques-Mandé Daguerre and introduced worldwide in 1839. By 1860, new processes which were less expensive and produced more easily viewed images had almost completely replaced it. During the past few decades, there has been a small-scale revival of daguerreotypy among photographers interested in making artistic use of early photographic processes. To make a daguerreotype, the daguerreotypist polished a sheet of silver-plated copper to a mirror finish; treated it with fumes that made its surface light-sensitive; exposed it in a camera for as long as was judged to be necessary, which could be as little as a few seconds for brightly sunlit subjects or much longer with less intense lighting; made the resulting latent image on it visible by fuming it with mercury vapor; removed its sensitivity to light by liquid chemical treatment; rinsed and dried it; then sealed the easily marred result behind glass in a protective enclosure. Viewing a daguerreotype is unlike looking at any other type of photograph. The image does not sit on the surface of the metal, but appears to be floating in space, and the illusion of reality, especially with examples that are sharp and well exposed is unique to the process. The image is on a mirror-like silver surface, normally kept under glass, and will appear either positive or negative, depending on the angle at which it is viewed, how it is lit and whether a light or dark background is being reflected in the metal. The darkest areas of the image are simply bare silver; lighter areas have a microscopically fine light-scattering texture. The surface is very delicate, and even the lightest wiping can permanently scuff it. Some tarnish around the edges is normal, and any treatment to remove it should be done only by a specialized restorer. Several types of antique photographs, most often ambrotypes and tintypes, but sometimes even old prints on paper, are very commonly misidentified as daguerreotypes, especially if they are in the small, ornamented cases in which daguerreotypes made in the US and UK were usually housed. The name "daguerreotype" correctly refers only to one very specific image type and medium, the product of a process that was in wide use only from the early 1840s to the late 1850s. ==History== Since the Renaissance era, artists and inventors had searched for a mechanical method of capturing visual scenes. Previously, using the camera obscura, artists would manually trace what they saw, or use the optical image in the camera as a basis for solving the problems of perspective and parallax, and deciding color values. The camera obscura's optical reduction of a real scene in three-dimensional space to a flat rendition in two dimensions influenced western art, so that at one point, it was thought that images based on optical geometry (perspective) belonged to a more advanced civilization. Later, with the advent of Modernism, the absence of perspective in oriental art from China, Japan and in Persian miniatures was revalued. In the early seventeenth century, the Italian physician and chemist Angelo Sala wrote that powdered silver nitrate was blackened by the sun, but did not find any practical application of the phenomenon. Previous discoveries of photosensitive methods and substances—including silver nitrate by Albertus Magnus in the 13th century, a silver and chalk mixture by Johann Heinrich Schulze in 1724, and Joseph Niépce's bitumen-based heliography in 1822 contributed to development of the daguerreotype.〔〔(【引用サイトリンク】url=http://www.hrc.utexas.edu/exhibitions/permanent/wfp/heliography.html )〕 The first reliably documented attempt to capture the image formed in a camera obscura was made by Thomas Wedgwood as early as the 1790s, but according to an 1802 account of his work by Sir Humphry Davy: "The images formed by means of a camera obscura have been found too faint to produce, in any moderate time, an effect upon the nitrate of silver. To copy these images was the first object of Mr. Wedgwood in his researches on the subject, and for this purpose he first used the nitrate of silver, which was mentioned to him by a friend, as a substance very sensible to the influence of light; but all his numerous experiments as to their primary end proved unsuccessful."〔(【引用サイトリンク】title=An Account of a method of copying Paintings upon glass, and of making Profiles, by the agency of Light upon Nitrate of Silver. Invented by T. Wedgwood, Esq. With Observations by H. Davy. (1802) )〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「daguerreotype」の詳細全文を読む スポンサード リンク
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