The pioneers
When a group of inventors decided in the early 1800's that it might be possible to spread some chemicals on a piece of paper and in this way permanently capture an image projected by a camera obscura, their theories must have seemed ridiculous, but these inventors were completely serious. They were sure that the seemingly magical act of preserving an image on paper was possible.
In the 1720's, the German scientist Heinrich Schulze had shown that some naturrally occurring chemicals (all of which were comprised in large part of powdered silver compounds) would darken when exposed to light. Before Schulze's studies, it had been believed that these changes were due to heat. Yet until 1802 that a British man named Thomas Wedgwood thought to use this phenomenon to try to make pictures. Wedgwood's father, Josiah, was a famous potter who used a camera obscura to help him create complicated designs on his pottery. Thomas felt that he could go one better, as a friend of his, the chemist and inventor Humphry Davy, wrote in an 1802 journal article. ''White paper, or white leather, moistened with a solution of nitrate of silver, undergoes no change when kept in a dark place, but on being exposed to the day light, it speedily changes color.'' Davy explained. ''Outlines and shades of paintings on glass may be copied, and profiles of figures procured, by the agency of light.''
Specifically, when the coated paper or leather was placed behind a painting on glass and exposed to the sun, ''the rays transmitted through the differently painted surfaces produce distinct tints of brown or black,'' Davy wrote. These tints differed in darkness depending on the colors of the picture itself. The coated paper stayed lightest where the dark tones of the picture prevented much light from coming through the glass and turned black were the sun struck it directly.
In other words, the coated paper produced a negative photographic image, of the painting on the glass above. Unfortunately, the same technique didn't work for the inventor who tried to capture images from life, rather than from paintings. The image projected by the camera obscura was too faint to make any impression on the paper.
What's more, there was no way to prevent the image from darkening further on exposure to more light Wedgwood could not ''fix'' it once it had reached the right levels of darkness and light. As Davy explained, ''The copy of the painting, immediately after being taken, must be kept in an obscure place. it may indeed be examined in the shade, but in this case, the exposure should just be for a few minutes.'' Even then, the image would gradually darken, until soon it looked like nothing more than a picture of a black night.
Thomas Wedgwood must have realized that some way would have to be found to make the images truly permanent, but he died in 1806, before he had the chance to search for a solution. Those efforts were left to a French inventor named Joseph Nicéphore Niepce. Working in a small house in Le Gras, France, Niepce to became interested in trying to use paper coated with silver compounds to reproduce images from life. Unlike Wedgwood, though, Niepce strove to be able to produce paper sensitive enough to detect the faint images projected by the camera obscura. In 1816 he also built a camera that would make this more likely by casting a stronger image on the paper. In a letter to his brother Claude, he called his first try an ''artificial eye, which is nothing byt a small box sin inches square; the box will be equipped with a tube that can be lenghtened, and will carry a lenticular lens.''
When this camera broke, Niepce wasn't discouraged. To replace it, he used a jewel case and the lens from a microscope to build the world's first miniature camera, just one and one-half inches square. He then placed this camera in this attic workroom, facing the window, so that it projected an image of a nearby birdhouse onto a piece of coated paper. ''I saw on the white paper all that part of the bird house seen from the window,'' he wrote to Claude. ''The background of the picture is black, and the objects white, that is, lighter than the background.''
Niepce had produced the first photographic negative of the real world, a picture that was pergectly accurate, except that the dark tones of nature were represented as light on the paper, and the areas of greatest brightness appeared as dark patches. What's more, he was even able to partially fix the image keep it from darkening by washing it in nitric acid.
Even so, Niepce himself was skeptical of his achievement and unimpressed by the image. ''The effect would be still more striking,'' he told his brother, ''if the order of the shadows and the lights could be reversed.'' unfortunately, though, Niepce never figured out how to produce a positive image from his negative one. Neither was he able to figure out how to make additional copies from his original.
Instead he tried to capture an image on a printing plate. ''With a patience anything can be done,'' Niepce told Claude, and patience was certainly what he needed. For years, he methodically tried one technique after another, coating metal plates with various substances. Finally, in 1822, he came upon something that worked: a type of asphalt called bitumen of Judea, which was usally used to surface roads. When exposed to light, the dark bitumen would fade to a slightly lighter color. Even more importantly, the exposed surfaces would turn rock hard, while unexposed surfaces would stay softer. Niepce called these images on asphalt ''heliographs,'' or ''sun pictures.''
Niepce had proven that he had both the patience and crativity to overcome problems that had stymied many inventors before him. Try as he might, however, he couldn't seem to take the last steps toward making his inventions a commercial success. He needed a partner, preferably one with a stronger business sense. He ended up with French inventor Louis Jacques Mandé Daquerre. Daquerre, was a cheerful, outgoing man who loved attention and publicity.
Daquerre used a camera obscura to help create the Diorama's giant paintings, projecting and tracing the church scene and others, and then using the tracings to produce the most accurate paintings possible, but this was laborious, exremly time consuming work. Wouldn't it be wonderful, Daguerre dreamed, if somehow the painting could be replaced by an image reproduced directly from life?
When he heard that a man named Niepce was working tomards a similar goal elsewhere in France, Daquerre wasted no time in contacting th eolder inventor. In 1827 they met in Paris, where Niepce viewed his first two Dioramas, both of which showed outdoor landscapes. Describing them to his son Isidore, he wrote, ''These representations are so reaal, even in their smallest detail, that one believes that he actually sees rural and primeval nature with all the fascination with which charm of colors and the magic of light and shade endow it.''
Daquerre was equally impressed with Niepce's heliographs. Daquerre knew that these faint, faded images were far from the quality he'd needed for his Diorama, but he also saw that the achievement was an important one with great potential.
In the 1720's, the German scientist Heinrich Schulze had shown that some naturrally occurring chemicals (all of which were comprised in large part of powdered silver compounds) would darken when exposed to light. Before Schulze's studies, it had been believed that these changes were due to heat. Yet until 1802 that a British man named Thomas Wedgwood thought to use this phenomenon to try to make pictures. Wedgwood's father, Josiah, was a famous potter who used a camera obscura to help him create complicated designs on his pottery. Thomas felt that he could go one better, as a friend of his, the chemist and inventor Humphry Davy, wrote in an 1802 journal article. ''White paper, or white leather, moistened with a solution of nitrate of silver, undergoes no change when kept in a dark place, but on being exposed to the day light, it speedily changes color.'' Davy explained. ''Outlines and shades of paintings on glass may be copied, and profiles of figures procured, by the agency of light.''
Specifically, when the coated paper or leather was placed behind a painting on glass and exposed to the sun, ''the rays transmitted through the differently painted surfaces produce distinct tints of brown or black,'' Davy wrote. These tints differed in darkness depending on the colors of the picture itself. The coated paper stayed lightest where the dark tones of the picture prevented much light from coming through the glass and turned black were the sun struck it directly.
In other words, the coated paper produced a negative photographic image, of the painting on the glass above. Unfortunately, the same technique didn't work for the inventor who tried to capture images from life, rather than from paintings. The image projected by the camera obscura was too faint to make any impression on the paper.
What's more, there was no way to prevent the image from darkening further on exposure to more light Wedgwood could not ''fix'' it once it had reached the right levels of darkness and light. As Davy explained, ''The copy of the painting, immediately after being taken, must be kept in an obscure place. it may indeed be examined in the shade, but in this case, the exposure should just be for a few minutes.'' Even then, the image would gradually darken, until soon it looked like nothing more than a picture of a black night.
Thomas Wedgwood must have realized that some way would have to be found to make the images truly permanent, but he died in 1806, before he had the chance to search for a solution. Those efforts were left to a French inventor named Joseph Nicéphore Niepce. Working in a small house in Le Gras, France, Niepce to became interested in trying to use paper coated with silver compounds to reproduce images from life. Unlike Wedgwood, though, Niepce strove to be able to produce paper sensitive enough to detect the faint images projected by the camera obscura. In 1816 he also built a camera that would make this more likely by casting a stronger image on the paper. In a letter to his brother Claude, he called his first try an ''artificial eye, which is nothing byt a small box sin inches square; the box will be equipped with a tube that can be lenghtened, and will carry a lenticular lens.''
When this camera broke, Niepce wasn't discouraged. To replace it, he used a jewel case and the lens from a microscope to build the world's first miniature camera, just one and one-half inches square. He then placed this camera in this attic workroom, facing the window, so that it projected an image of a nearby birdhouse onto a piece of coated paper. ''I saw on the white paper all that part of the bird house seen from the window,'' he wrote to Claude. ''The background of the picture is black, and the objects white, that is, lighter than the background.''
Niepce had produced the first photographic negative of the real world, a picture that was pergectly accurate, except that the dark tones of nature were represented as light on the paper, and the areas of greatest brightness appeared as dark patches. What's more, he was even able to partially fix the image keep it from darkening by washing it in nitric acid.
Even so, Niepce himself was skeptical of his achievement and unimpressed by the image. ''The effect would be still more striking,'' he told his brother, ''if the order of the shadows and the lights could be reversed.'' unfortunately, though, Niepce never figured out how to produce a positive image from his negative one. Neither was he able to figure out how to make additional copies from his original.
Instead he tried to capture an image on a printing plate. ''With a patience anything can be done,'' Niepce told Claude, and patience was certainly what he needed. For years, he methodically tried one technique after another, coating metal plates with various substances. Finally, in 1822, he came upon something that worked: a type of asphalt called bitumen of Judea, which was usally used to surface roads. When exposed to light, the dark bitumen would fade to a slightly lighter color. Even more importantly, the exposed surfaces would turn rock hard, while unexposed surfaces would stay softer. Niepce called these images on asphalt ''heliographs,'' or ''sun pictures.''
Niepce had proven that he had both the patience and crativity to overcome problems that had stymied many inventors before him. Try as he might, however, he couldn't seem to take the last steps toward making his inventions a commercial success. He needed a partner, preferably one with a stronger business sense. He ended up with French inventor Louis Jacques Mandé Daquerre. Daquerre, was a cheerful, outgoing man who loved attention and publicity.
Daquerre used a camera obscura to help create the Diorama's giant paintings, projecting and tracing the church scene and others, and then using the tracings to produce the most accurate paintings possible, but this was laborious, exremly time consuming work. Wouldn't it be wonderful, Daguerre dreamed, if somehow the painting could be replaced by an image reproduced directly from life?
When he heard that a man named Niepce was working tomards a similar goal elsewhere in France, Daquerre wasted no time in contacting th eolder inventor. In 1827 they met in Paris, where Niepce viewed his first two Dioramas, both of which showed outdoor landscapes. Describing them to his son Isidore, he wrote, ''These representations are so reaal, even in their smallest detail, that one believes that he actually sees rural and primeval nature with all the fascination with which charm of colors and the magic of light and shade endow it.''
Daquerre was equally impressed with Niepce's heliographs. Daquerre knew that these faint, faded images were far from the quality he'd needed for his Diorama, but he also saw that the achievement was an important one with great potential.
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To make a daguerreotype, each copper plate had to be coated by hand with light-sensitive material.
He believed that all it would take was hard work to make photography a reality. The two men became partners in 1829, and indeed Daquerre began to work hard, disappearing into his laboratory for days on end. ''He is always at the thought; he can't sleep at night, I am afraid he is out of his mind.'' his wife complained in a letter to a friend.
Daquerre and Niepce both continued to struggle to improve the potential of heliography. Within a year or two, though, Daquerre had given up on using bitumen of Judea and focused on coating paper with light-sensitive silver compounds, as Thomas Wedgwood had done, only Daguerre mixed the silver powder with iodine to increase its sensitivity to light.
In 1834, four years after Niepce's sudden death, Daguerre came up with a silver-iodine technique that worked. He placed a copper plate, coated with silver and carefully polished, into a box containing called silver iodine vapor. This vapor mixed with the silver coating to form a compound called silver iodine, which is very light sensitive.
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After being coated in a special ''coating box,'' the plate was inserted into a camera and exposed to light as the daquerreotype was taken. The image captured on the plate was then developed (by exposure to mercury vapor heated over a lamp), fixed (by treatment with the chemical hydrosulphite), rinsed, and then dried. It was a slow difficult process, but better than anything that came before.
Daquerre then placed the sensitized plate inside a camera, still a simple box with a lens, as it had been for centuries and took a picture. At the beginning, this meant exposing the plate to a brightly lit scene for at least fifteen or twenty minutes. Though this was still a long time by today's standards, it was a vast improvement over the eight hours Niepce had needed to form an image on his bitumen-covered plate. After the exposure was completed, Daquerre put the plate into a box containing mercury vapor. The mercury interacted with the specks of silver that had formed where the sun had struck to creae large pale spots, which to the eye formed silvery patterns corresponding to the lightest objects in the scene that had been photographed. The dark polished silver of the unexposed portions of the plate, where the sunlight-silver-mercury interaction hadn't taken place, represent the darker areas of the scene. In one more advance, perhaps the most important of all, Daquerre was able to make the image permanent by washing the plate in a salt solution. He then discovered that he could achieve a better result by using a salt coumpound, sodium thiosulphate (hypo), which dissolved and removed all the unexposed silver iodide, making the plate permanent.
Daguerre, never shy, named his process the daquerreotype, and the name soon caught on. More poetically, others took to calling it ''the mirror with a memory.''
When Daquerre announced his process in January 1839, the public and press were very enthusiastic. Due to his spectacular Dioramas, Daquerre was already known to be able to work wonders. By inventing his ''mirror with a memory'', he'd created his greatest trick so far, and this one was no illusion.
Gazing at the first daquerreotypes on display in Paris, people were stunned by the images' clarity and detail. ''From today, painting is dead!'' the great painter Paul Delaroche supposedly said, and others were just as amazed. Describe a picture of a bridge and wharf along the River Seine in Paris, a writer in an American magazine exclaimed, ''All the minutest indentations and divisions of the ground, of the building, the goods lying on the wharf, even the small stones under the water at the edge of the stream, nd the different degrees of transparency given to the water, were all shown with the most incredible accuracy.'' Photography had came a very long way since Niepce had made his first heliograph twelve years earlier.
Having seen Daguerre's creations, people immediately wanted to take daguerreotypes for themselves. In August 1839, a Paris lecture by Daguerre's associates, followed by the publications of a brochure explaining every step of the process, sent dozens of hopeful photographers to shops to buy the boxes, lenses, plates, and chemicals necessary to make daquerreotypes. ''Everyone wished to copy the view from his window,'' reported a writer of the time named Gaudin. Each new photographer, he added, ''went into ecstasies over chimney tops, he counted again and again rood tiles and chimney bricks, he was astonished to see the very mortar between the bricks in a word, the technique was so new and seemed so marvelous that even the poorest proof gave him an indescribable joy.''
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Because of the long exposure time, this 1839 daguerreotype of a busy Paris street looks almoast deserted. Anything that moved didn't register. In fact, a man who was having his shoes shined is the only one who stood still long enough to show up in the picture.
While this excitement was taking hold, Daquerre himself quickly lost interest in this public passion, choosing instead to go back to an older form of artistic expression: painting. Almoast immediately, though, other inventors began working in improve the process. One, William Henry Fox Talbot, had been working in England on a very different photographic technique of his own since 1833, the year that Joseph Niepce died. Like others with the same charming idea, Talbot went to his laboratory and began to experiment with coating paper, instead of plates. The idea came to him, he said, as he experimented with projecting images with a camera obscura into a piece of white paper. ''How charming it would be if it were possible to cause there natural images to imprint themselves durably, and remain fixed upon the paper!'' he wrote.
Like others with the same charming idea, Talbot went to his laboratory and behan to experiment with coating paper with silver compounds, and soon found that it was possible to reproduce a real-life scene projected through the camera obscura. Again like others, he also discovered that the image faded away to nothing if exposed even to weak light. At first Talbot, like Daguerre, preserved his images by bathing them in a strong salt solution. This bath was at least partly effective. No longer was it necesary to view pper photographs by candlelight in a dark room. At the suggestion of the scientist Sir John Herschel, he also began to use sodium thiosulphate (hypo) to make his images permanent.
Talbot called his images ''photogenic drawings.'' Since the paper's lightsensitive coating darkened on exposure to the sun, they were negative images that is, all the tones were reversed, with the dark parts appearing light, and vice versa. Talbot realized that in order to make his pictures lifelike he had to reverse the tones, and he soon devised a clever, easy way to transform these negative images into positive ones.
He waxed a completed photogenic drawing turning the paper surrounding the image transparent then laid it atop another piece of coated, light-sensitive white paper and exposed the whole thing to sunlight. The sunlight came strongly through the lighter portions of the original, turning those portions of the copy underneath dark. Meanwhile, the dark parts of the original blocked the sunlight, leaving those areas of the copy in white. This process produced a black-and-white image whose tints corresponded with those in real life. As an added bonus, by using this technique, Talbot found that he could make as many positive images as he wanted by repeating the process.
What Talbot did, in the most basic possible way, was invent the photographic negative and the positive print. Today, we use the same ideas that this British inventor, working on his own, came up with more than one hundred and fifty years ago.
Talbot announced his inventions to the world soon after Daquerre did in 1839. He renamed his photographic images ''calotypes,'' though for a while the public and press thought of them as ''talbotypes.'' No matter the name, his new process especially its ability to produce infinite numbers of copies of an image was a direct threat to the daquerreotype, with its heavy metal plate and single image that couldn't be reproduced. A lively competition between the two techniques would last for years. Talbot's calotype was never as popular as the daquerreotype, but the negative/positive principle was the basis of modern photographic systems.