Among the many amazing inventions made in the XIX century, it is not the last place is occupied by photo - art, allowing you to make instant picture of any object or landscape. Photo was born on the border of two disciplines: optics and chemistry, as for prints had to resolve two difficult problems. Firstly, it was necessary to have a special light-sensitive plate, the ability to perceive and hold on the image itself. Secondly, it was necessary to find a special device, which would clearly projected the image of the subject on the record. Both managed to create only after much trial and error. photos Wonder not at once was given into the hands of the people, and at different times, many inventors from different countries enthusiastically engaged in this issue.
Approaches to it can be found in the works of medieval alchemists. One of them, Fabricius, once mixed in his laboratory table salt with a silver nitrate solution and was milky-white precipitate, which was black from sunlight. Fabricius investigated this phenomenon in his book on metals, published in 1556, he said that with the help of the lens to obtain an image on the surface of the sediment, now known under the name of chloride of silver, and the image it is black or gray depending on the light duration of its solar rays. It was the first experience in the history of photography. In 1727, a doctor from Halle Johann Schultz did experiments with a solution of silver nitrate on a sunny day and chalk mixture which he covered in a glass vessel. When the container is exposed to sunlight, the surface of the mixture immediately turned black. While shaking the solution became white again. By Schultz received pieces of paper on the surface of the liquid silhouettes by shaking destroying them and getting new designs. These original experiments seemed to him only fun, and it took another hundred years before noticed by them property of silver chloride smart enough to be used in the manufacture of photographic plates.
Next page in the history of photography is associated with the name of Thomas Wedgwood. He put on paper, moistened with a solution of silver nitrate, the leaves of plants. At the same time covered with leaves of the paper remained light illuminated the blackened portion. The result of this experiment was a white silhouette on a black background. However, these images can be viewed only by the light of a candle, since sunlight they spoil. Wedgwood tried to infiltrate the skin with a solution and found that the images appear on it faster. (At the time of this phenomenon remains unexplained. Only in the late 30-ies of the XIX century it was found that the tannic acid in the skin, greatly accelerates the display of the image.) In 1802, Wedgwood has published the results of their experiments. Gradually he learned to get the contour image on the paper, leather and glass within three minutes - with their exposure to the sun, and within a few hours - by exposing them in the shade. But these pictures are not transferred to sunlight, as they were not captured. Only in 1819, John Herschel found a substance that strengthens the photographic image. They found sernovatistokisly soda. It would seem that photography had to do the last step to take place completely as an art, but this step was taken only twenty years later. In the meantime, the search for the inventors took a different path.
In 1813, for experiments with photographic plates Niépce began a French artist who owns the main merit of the invention of the camera. Around 1816 he came to the idea of getting an image of objects by means of a so-called camera obscura. This camera has been known since ancient times. In its simplest form it is tightly closed on all sides by a light-tight box with a small hole. If the wall opposite the hole will be of frosted glass, then it turns out inverted image of objects located in front of the camera. The smaller the aperture, the sharper the contours of images and so it is weaker. In the course of centuries, the effects observed in the camera obscura, fascinated nature lovers. In 1550 Cardan gave Nuremberg the camera with a large hole where the lens is. So he got a brighter and sharper image. This was an important improvement as well lens collects the rays and significantly improved the observed effect. It is a dark box with a very small aperture and the lens on one side and the light-sensitive plate to another Niepce decided to use for image projection. It was the first camera in the history.
In 1824 Niepce managed to solve the problem of fixing the images obtained in the camera obscura. Unlike his predecessors, he did not work with silver chloride, and did experiments with rock resin, which is under the influence of light has the ability to change some of its properties. For example, the light is stopped to dissolve in certain liquids, which dissolve in the dark. Mountain covered with a layer of resin copper plate, Niepce insert it in the camera obscura, and put the magnifying glass in focus. After a fairly long-acting light plate was removed and immersed in a mixture of oil of lavender oil. In the field, containing the effect of light, mountain resin remained intact, and the rest of it is dissolved in the mixture. Thus, the place is completely covered with resin, were lit places, and covered only in part - the penumbra. Pattern required to obtain at least 10 hours as the resin changed by light is very slow.
It is clear that this method was difficult to call the perfect and Niepce continued to search. In 1829 he joined forces with Louis-Jacques Daguerre, a former officer, a decorator at the Paris theater, worked on the same issues. Soon he died and Daguerre continued the research one. He already had before the camera, invented by Niepce, but still did not know how to obtain a light-sensitive plate. A whole series of amazing coincidences brought him eventually to the right path. Once Daguerre accidentally put a silver spoon on a metal coated with iodine, and noticed that the metal to obtain an image of a spoon. Then he took a polished silver plate and subjected to the action of its iodine vapor, to thereby obtain a silver iodide. At the plate, he put one of the photographic images Niepce. After some time, her image formed copy, but it is very unclear, so that it can be distinguished only with difficulty. Nevertheless, it was an important result, it opens the photographic properties of silver iodide. Daguerre began to look for the way in which it would be possible to show the images obtained. Another lucky break led to an unexpected success. Once Daguerre took the dark room plate left there, with which he worked the day before, and to the great surprise saw her weak picture. He suggested that a substance had an effect on the plate and showed for the night on the eve of the invisible image. many chemicals are in a dark room. Daguerre took up the search. Every night he put a new plate in the pantry every morning and cleaned it out with one of the chemical reagents. He repeated these experiments until, not yet removed from the room all the chemicals and put the new album is already on an empty shelf. To his surprise, the morning of this record, too, was manifested. He carefully inspected the room and found it a bit of spilled mercury: its vapor and were chemical developer. After that Daguerre was already able without any difficulty to develop all parts of the photographic process - with the camera he got a faint image on the plates coated with silver iodide and then showed them the mercury vapor. The result came out remarkably clear images of objects with all the fine detail and halftones. Perennial search culminated a remarkable discovery.
August 10, 1839 in Paris there was a big meeting with members of the Academy of Sciences. It was announced that Daguerre discovered a way to exercise and fix the photographic image. Post it made a huge impression. The whole world discussed the opportunities presented by the new achievements of human thought. The French government bought the secret invention, Daguerre and appointed him a lifetime pension of 6,000 francs. Not forgotten and son Niepce. Soon on sale appeared sets for photographing by the method of Daguerre (this method became known as daguerreotypes). Despite the high price, it was sold out in a short time. But soon the audience felt a strong cooling of this invention. Indeed, daguerreotypes, although it gave good results, require enormous effort and much patience.
daguerrotypist work begins with cleaning and polishing silvered copper plate. This work was carried out very carefully, first by alcohol and cotton wool, and then - iron oxide and soft skin. In no case could not touch the plate with his finger. Final polishing was done already before the actual recording. Thereafter, silver plate made sensitive to light. For this purpose, it was placed in a dark box with dry iodine. Depending on what is going to shoot - landscape or portrait - the duration of treatment with iodine vapor was different. Thereafter, for several hours plate becoming photosensitive, and it was placed in the cassette. The tape was a small flat wooden box with two movable walls - the back opened on hinges of the door, and the front - climbed up and down the special cursor in the progression. Between these doors and the plate was.
The first camera is an advanced camera obscura. In the open box with one side moving back and forth the other box which can be held in position by a screw. On the front wall of the box was a lens or a microscope slide, and on the back side - frosted glass. Soon Charles Chevalier began to use instead of a single lens two, are designed so the first lens. Rays from an external object, after passing through the lens stayed on the ground glass, and at a proper distance from the latter subject was represented by its clear image. Greater or less distinctness of image achieved moving away or approaching the inner box and the lens permutation. When the desired clarity is achieved, the place of frosted glass tape was placed in such a way that, when inserted in the camera, the surface of the plate was in that place, which occupied the frosted glass in the moment when the image of the object was on it all more clearly. Then he took out the cassette front cover and start shooting. The first sessions were so tedious, so the conditions are bad, the plate react so slowly that it had great difficulty to find people willing to act. I had to sit still for 20 minutes under the scorching sun to get good at the then notions portrait. Images of the eye in the first portraits did manage with great difficulty, so the earliest daguerreotypes, we see the face with closed eyes.
After the shooting tape closed and went into a dark room. Here, by the light of a candle plate removed. It could be seen barely perceptible image of the object. To it became clearer and clearer, it was necessary to show. This operation is performed by means of mercury vapor. In wooden box with copper bottom poured a bit of mercury and placed in it the image of a plate down. To expedite the process, placed at the bottom of the burning alcohol lamp. Mercury began to evaporate rapidly and showed the image. Daguerrotypist watched the process side through a special little window. After the image was shown clearly enough, the plate was removed. Where the light acted most strongly, an iodine compound with silver weakened the most, and why mercury is pristyvala tiny droplets that form a white surface. The semitones for accession Mercury there more obstacles, and mercury in dark places and at all could not stick to undecomposed layer of silver iodide. Because penumbra out more or less grayish and pure silver seemed completely black.
To remove residues of unreacted silver iodide plate had to be fixed. For this it is placed in sernovatistokislogo hydroxide solution which dissolves silver iodide, which underwent no effect of light. Finally, the plate was washed in water and dried. As a result of all these manipulations were obtained on the plate beautifully clear image in which each item is transmitted with remarkable clarity. But in order for the image persisted longer it had to be strengthened. To this plate was poured weak solution of gold chloride and heated in an alcohol flame. In this reaction, chlorine chloride was connected to gold and silver, and gold were allocated in the form of metal and covered the image very thin barrier film. This operation also removes unpleasant silver mirroring.
This photograph is presented to us in the first years of its existence. From this brief description it is clear that it was not only tedious but also very harmful to the health of workers. However, in an image immediately got a lot of admirers and enthusiasts. They were ready to spend hours breathe fumes of iodine or mercury, enthusiastically watching as plates mysteriously manifested image. That it is an art owes its rapid improvement.
First of all, renewed experiments with paper impregnated photosensitive composition - it became known as photo paper. These experiments early in the century spent Wedgwood. In the same 1839 Fock Talbot found that if the photo paper that even a short time exposed to the light handle galusovoy acid, the picture appears very quickly. Similarly, as mercury is a silver surface image galusovaya acid causes it to paper. The following year, Professor Goddard in London found that increases in the several tens of times the replacement of silver iodide bromide, the emulsion sensitivity. Due to this the time necessary for shooting an object, immediately decreased from 20 minutes to 20 seconds. Then Claude found that bromine increases the sensitivity of iodized silver plates, so that a few seconds were enough to produce an image. After these discoveries, made possible the development of photography in the modern sense of the word.
In photography, silver, coupled with iodine, chlorine and bromine, played a major role in getting the image. Under the influence of light the compounds disintegrated and released in the form silver fine particles, forming a substance that paints, in the same way as in daguerreotypes mercury. All occurring when photographing chemical reactions can demonstrate a few simple experiments. If the tube with brine to pour some drops of silver nitrate, the reaction of the two substances, a white curdy precipitate of silver chloride. In the sunlight this precipitate in a short time lost its white light and becomes the first purple, then gray and finally - black. The fact that the light silver chloride decomposes, and wherein the metallic silver is released. However, this change undergo only the layers that are closer to the light. If you add a few drops of a solution of soda sernovatistokislogo, most of silver chloride is gradually dissolved. Undissolved flakes will only evolved under the influence of light metallic silver. In these reactions, the entire course of operations presented in the photos.
To prepare a photographic paper, taking good white sheet of writing paper and wetted with it in 10% sodium chloride solution, dried and lay on the surface of the silver nitrate solution. The resulting paper formed on the photosensitive layer of silver chloride. The finished sheet was placed in a light-tight cassette, and the picture is the same as described above. At the same time after the occurrence of paper turned a visible image of the object, but not the direct and the inverse, that is the brightest place went to her darkest and the darkest - remained bright. This was because wherever photosensitive layer was subjected to intensive action of light, frees the greatest amount of metallic silver black. Conversely, where the effect of light was slightly remained white silver chloride. This image was fixed by washing the sheet in a solution of soda sernovatistokislogo. But it is clear that use of such photos that gave a completely opposite image of light and shadow, it was uncomfortable. It was used to produce positive prints. For this purpose, it was placed in the dark on the sensitive paper sheet in a copying frame, capped glass plate and exposed to light. Last penetrated the top put a negative image. Total easier it passed through quite bright place, weaker - through halftones and almost does not penetrate through the shadows. Because on the bottom sheet of sensitive paper obtain the desired positive image which, after sufficient light, and was taken out and strengthened.
However, for all these operations is insufficient paper suitable material, because it has a rough structure and inhibits the passage of light. Clean the glass in its transparency would constitute the best material, but it was not able to absorb chemical substances, so turn it into a light-sensitive plate was not as easy as paper. Out of this difficulty was found quickly - a glass plate were covered with a thin transparent adhesive film, capable of holding a photosensitive layer. First, for this use egg whites, and then collodion. The latter method was opened in 1851. Scott Archer.
Photographic collodion solution consisted of a rattlesnake cotton paper with alcohol and ether was a colorless mucous fluid, which in thin layers quickly dried up, leaving a transparent film. For a glass photographic plate collodion cadmium iodide solution was added. Then we take a clean glass plate and poured on it a sufficient number of collodion. When the collodion dries to a thick mass, the plate was immersed in a silver nitrate solution saturated with silver iodide. In this reaction, iodine and bromine were combined with silver to form silver bromide and iodide, which is deposited in a layer of collodion. On the contrary, nitric acid is released from the silver salt was combined with cadmium. Thus, the plate was covered with a photosensitive layer, and was ready to shoot. To display the image it was treated with a solution of pirogalusovoy acid or a solution of ferrous sulfate (iron sulfate + water + acetic acid + alcohol). Acetic acid slows down response to the manifestation of not going too fast. Securing happened, as before, a solution sernovatistokislogo hydroxide. To download and obtain the final image has served as photo paper coated with silver chloride. Photographing at Collodi was the beginning of modern photography; from that time made possible to easily and quickly get a good, crisp images.