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The technology derived from the ancient camera obscura was the first step on the road to modern digital technology. It achieved the first basic task - the beginnings of an understanding of how to focus light - specifically onto a surface. Yet this was still a far cry from the ability to record the light so that it would be visible after the darkness of the camera obscura had been violated. Other than advancements using a camera obscura as a drawing tool very little about the technology changed until the 1700s when a major breakthrough in the art took place entirely by accident.
 Johann Heinrich Shulze
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In 1727 a German professor of anatomy named Johann Heinrich Shulze was performing research on certain materials which had unusual properties. There was some scientific understanding at the time that certain minerals would darken over time. The question was whether the darkening could be attributed to exposure to light or exposure to heat.
After burning some silver nitrate - one of the materials in question - produced no darkening he mixed a combination of chalk, nitric acid and silver together in a flask producing silver chloride and silver nitrate - the silver salts. Some of the mixture got on the flask in which he had produced the concoction and Proffessor Shulze noticed that the side of the flask which had been exposed to the sun had darkened noticeably. He had inadvertently discovered the first photosensitive materials - a discovery which would make all further photographic discoveries possible.
Even after Shulzes groundbreaking discovery development was slow. Some early photographic pioneers experimented with the silver nitrate. Proffesor Shulze himself performed further experiments before his passing in 1744. Sadly he never had success in permanently affixing an image to a material for if exposed the light for long enough all the silver nitrate would darken and the image would be lost.
The next major development - indeed what could be considered the birth of "modern" photography came at the hands of a young Englishman: Thomas Wedgewood. Born in 1771 to a family of potters. Up until his abrupt death in 1805, Wedgewood was passionately involved in the field of education. In his spare time he attempted to create permanent images as a visual aide to help young children learn. This led to his experimentations in photography
Thomas Wedgewood
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As early as the 1790s, along with contemporary colleagues such as Sir Humpry Davy and James Watt, Wedgewood experimented with silver nitrate attempting to create permanent images. He affixed the silver nitrate to different surfaces such as clay pots and then exposed it to light. He found great success, especially when putting the silver nitrate onto sheets of white leather. Using silhouettes he shaded the material from light and created a selective pattern of negative space. These simple photographs he called sun pictures" and it was observed that as long as the resulting image was not exposed to extreme light it would last for some time. While far from perfect these were huge steps and are considered to be the first true photographs.
The developments in photosensitive materials continued. Techniques where developed to produce photosensitive paper but it wasnt until 1816 that the next monumental development of all took place. A French scientist - Nicephore Niepce - doing research on preserving images formed on photosensitive paper made the brilliant leap to expose photosensitive paper to the light of a camera obscura. He met with much initial failure but continued his research using this new technique.
 Joseph Nicephore Niepce
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In 1826 Niepce spent eight hours exposing what would be the first permanent photographic print to the light of a camera obscura. Niepce called his image a "heliograph" and while the print still exists - housed under glass at the University of Texas at Austin - controversy remains as to the exact methods used to produce the print. It is supposed that he used bitumen - a photosensitive petroleum derivative - exposed to the light from a camera obscura. After the exposure he was able to seal the parts of the image still at risk of exposure and preserve the first permanent photograph.
Niepce passed away in 1833 and left his notes to his younger colleague - Louis Daguerre. However the major breakthrough of the 1830s came not from a Frenchman but from an English gentleman and polymath by the name of William Henry Fox Talbot. Talbot had also been experimenting with fixing permanent images to photosensitive paper using multiple applications of silver and salts. In a flash of intellectual brilliance he developed the calotype negative image process. Until that point all "photographs" were actually negative images - the areas of the photopaper which were exposed to light would darken and the shaded areas would stay light. Talbot surmised that it may be possible to create a fully positive image by imprinting a second sheet of paper from a photographic negative.
 Fox Talbot
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Over the next decade he continued his work making great strides and developments into the photographic process. Talbot is responsible for many developments in the field including the use of certain key acids to stabilize photographs and also developments in the field of optics. Unfortunately his patent on the calotype process called for expensive royalties and did not gain initial popularity.
Around the same time that Talbot was making his discoveries into the negative printing process Nicephore Niepce's young colleague Daguerre was putting Niepce's notes to good use. Daguerre developed a photographic method which he named after himself: daguerreotype. Daguerreotype photography used a piece of copper plated with silver and polished to a mirror shine. To this he affixed silver iodide and exposed it to the light of a small camera obscura. This was in turn developed or stabilized using slightly warmed mercury vapors. While this process may seem crude by modern standards it was revolutionary because it allowed complex and delicate images - such as a human portrait - to be captured and maintained for the first time.
Louis Daguerre
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Daguerre was aware of Talbots research and vice versa. When the daguerreotype techniques were first introduced to the world Daguerre did not patent them except in England in order to stifle Talbots research. Daguerre was offered a stipend by the French government in exchange for his technology and daguerreotyping quickly came into the public market.
Doubtless to the chagrin of Fox Talbot daguerreotype became a photographic standard over the entire world. Unlike Talbots process where the negative image could be used to produce multiple copies - superior technology by some standards - daguerreotype prints were each unique. Millions of daguerreotypes were produced - many of famous or influential individuals - but Daguerres glory would be short lived for by the time of his death in 1851 developments in Talbots negative technology - called the collodion process - would signal the end of the the daguerreotype process and herald in the next stage on the road to modern digital photography.
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