Photography is the process whereby light produces an image on a sensitized surface. The precursor of photography and the modern camera is the camera obscura (Latin for "dark chamber"). In its basic form, as developed by tenth-century Islamic scientists, the camera obscura was a darkened enclosure with a small aperture to admit light. The light rays would cast an inverted image of external objects onto a flat surface opposite the aperture. This image could be studied and traced by someone working inside the camera obscura, or viewed from the outside through a peep-hole. In the sixteenth century, the Italian scientist Giambattista della Porta (1538-1615) published his studies on fitting the aperture with a lens to strengthen or enlarge the image projected. Made increasingly versatile through additional improvements, the camera obscura become popular among seventeenth and eighteenth-century European artists--including, perhaps most notably, the Dutch painter Jan Vermeer (1632-1675). The essential challenge in the development of photography was to capture the image produced by a camera obscura in a permanent form. In 1727, the German professor of anatomy Johann Heinrich Schulze took a step in this direction by discovering that silver salts darkened when exposed to sunlight. Schulze "printed" words on a bottle by coating it with silver salts, attaching templates cut out of paper, and exposing the bottle to sunlight. Thomas Wedgwood (1771-1805), of the English pottery-works family, made some of the first attempts to actually "fix" such images and make them permanent. Wedgwood, however, only managed to produce transient silhouettes.
It was the French inventor Joseph Nicephore Niepce who first achieved Wedgwood's goal. One area of Niepce's experimentation derived from his interest in reproducing engravings lithographically. In lithography, an image is printed from a porous plate whose ink-receptive surface is partially drawn over with a hard, ink-repellent substance. Niepce's son, who was charged with drawing the lithographic plates, eventually left for military service. Therefore, Niepce tried to devise a way to "draw" the lithographic plates photographically. Niepce experimented with oiling engravings to make them transparent, placing them across plates that he had treated with a light-sensitive varnish, and then exposing the engraving-covered plates to sunlight.
In 1822, Niepce succeeded in this process. Niepce used bitumen of Judea, a form of asphalt, as the basis for the light-sensitive varnish. Sunlight would solidify the varnish only in areas under light portions of the engraving. After a period of exposure, therefore, Niepce could rinse the plate to obtain a photographic reproduction that could be used in lithographic printing. Using improvised cameras, Niepce also conducted more conventional photographic experiments. As early as 1816, Niepce captured an image of Paris on paper treated with silver chloride. The exposure time required was at least an hour, and Niepce could not adequately fix the image. By 1827, however, Niepce had achieved the first permanent photograph taken from nature, a view of his country estate. Niepce had fitted a professionally made camera obscura with a lens. Inside, he placed a pewter plate treated with the bitumen solution used in the lithographic experiments. To take the photograph, Niepce exposed the plate for approximately eight hours. After rinsing the plate, the lights were represented by solidified bitumen and the darks by the pewter background. Niepce termed his discovery heliography (Greek for "sunwriting").
In 1826, the French scene painter Louis-Jacques-Mande Daguerre, who wanted to exploit photographic images in creating theatrical backdrops, began corresponding with Niepce about heliography. This led to a commercial partnership that lasted from 1829 until Niepce's death in 1833. Working with copper plates coated with silver iodide, a technique he owed to Niepce, Daguerre discovered that a latent image, resulting from a relatively short thirty-minute exposure, developed fully when exposed to mercury vapor. Daguerre then used salt or sodium thiosulfate to fix the fully-formed image. Ignoring his debt to Niepce, Daguerre marketed this discovery as the daguerreotype. Although the daguerreotype produced a reversed left-to-right image, and the exposure time initially required precluded its use for portraiture, these impressively detailed and burnished photographs were an immediate commercial sensation in Paris.
During this same period, the English scientist William Henry Fox Talbot was attempting to capture a permanent photographic image on paper. To do so, Talbot first created a negative, in which light and dark tones are reversed. Talbot formed his negatives by placing patterned objects, such as twigs and lace, across transparent sheets of paper saturated with silver chloride. Talbot then exposed this ensemble to light. The silver chloride would darken except where covered by the objects, creating a reverse silhouette. After fixing the negative image with a salt or sodium thiosulfate solution, Talbot would place it against a fresh sheet of photosensitive paper. Exposing the pair of sheets to light would again reverse the image, yielding a positive photographic print. Talbot's 1835 image of his family estate (Lacock Abbey, Wiltshire) was the first negative-based photograph taken from nature in England. Talbot subsequently developed the calotype. Like the earlier daguerreotype, Talbot's breakthrough was based on developing a latent image though a separate chemical process, and thus reducing the exposure time required. With the calotype, an exposure time of a minute or less left an imperceptible negative image on light-sensitized, paper. This image was then developed in a wash containing gallic acid. Early cameras for Talbot's calotype consisted of wooden boxes fitted with a lens and partially lined with the photosensitive paper.
In 1839, fully aware of Daguerre's success, Talbot presented his calotype process to the Royal Society, Britain's premier scientific body. By 1841, Talbot had perfected his discovery and patented it under the name of talbotype. The talbotype method enjoyed two significant advantages over the daguerreotype: it allowed several positive prints to be obtained from a single negative, and the final image was not reversed. However, the talbotype photograph remained somewhat grainy. This soft-grained quality could be exploited for romantic artistic effects, but the daguerreotype's bright, finely-detailed image was generally considered superior.
Thus, it was not until the early 1850s, when the English portrait sculptor Frederick Scott Archer (1813-1857) promoted the collodion process, that the daguerreotype was superseded as the most popular form of photography. With Archer's process, glass plates were treated with a preparation of collodion (powdered cotton dissolved in ether). Once the solvents evaporated, a moist photosensitive film was left on the plate. This allowed for a finely-detailed negative to develop very rapidly, and positive paper prints could be taken from the negative for as long as it remained damp. The collodion process, which was widely used up through the 1880s, did have a significant limitation. As the glass plates had to be treated, exposed, and developed immediately, photographs could not be taken unless darkroom facilities, whether permanent or portable, were at hand. This drawback was partially balanced by the fact that the collodion process was never patented--an economically unwise self-effacement very much in contrast to the policies of Talbot and Daguerre.
The American inventor George Eastman benefitted far more than any of these predecessors from the mass-merchandising of photography and cameras. Eastman, who left school at the age of fourteen, developed a passion for photography while working as a bank clerk. Experimenting in his mother's kitchen, Eastman devised a way to coat glass photographic plates with a gelatin emulsion containing silver chloride. This emulsion, once solidified, left a light-sensitive "dry plate" that (unlike Archer's collodion-coated plates) would last indefinitely and could be developed at leisure. In 1879, Eastman developed a machine to mass produce his invention. In 1881, to market it, he founded the Eastman Dry Plate Company of Rochester, New York. Eastman's Dry Plate Company marked a new era in photography. Through his company, Eastman introduced several breakthrough products and procedures. The dry plate, sixty times more sensitive than those treated with collodion, meant that tripods were no longer mandatory to anchor the camera during exposure. In 1884, Eastman patented a photographic film, packaging it in a small plastic roll. Replacing plates with compact rolls of film enabled a welcome reduction to the size of cameras. In 1889, Eastman began producing a celluloid film that improved on his original paper-and-gelatin version. Eastman (who launched the trade name Kodak in 1888) ultimately marketed a highly innovative series of "folding," "hand," and "pocket" cameras that made photography accessible to even the casual amateur. Eastman-Kodak also exploited contemporary developments in color photography. The 35mm film format became the norm for non-instant photograophy.
In 1937, the American inventor Edwin Herbert Land founded the Polaroid company in Cambridge, Massachusetts. Land sponsored the next significant breakthrough in photography: the instant camera. During the 1940s, Land experimented with film systems that would rapidly and automatically generate positive photographic prints. In 1948, Land introduced the first such camera, the Polaroid Model 95. The film in the Model 95 consisted of sealed, two-sided packets. After a picture was taken, the camera would automatically eject a single two-sided packet though a set of rollers. As the packet passed through these rollers, a pod of developing chemicals would burst open. After one minute, during which the photograph developed, the packet could be separated into its two halves. The positive side displayed a sepia-toned image that quickly hardened and became permanent. The side coated with the negative emulsion was disposable.
Photography continues to grow in the second half of the twentieth century with the development of infra-red, ultraviolet, thermal, laser, electronic, and electromagnetic photographies, though these are often used in sophisticated technological applications. In the 1990s, the consumer photography market saw rapid, if not revolutionary, changes from traditional 35mm photography. In 1996, the Advanced Photo System (APS) was introduced. Developed jointly by Kodak and Fuji, two of the largest photography companies in the world, APS features smaller cameras and smaller 24 mm film. Though smaller, the film is more sophisticated, containing a magnetic strip which registers data about the conditions under which the photo was shot. This information is used in processing to correct exposure as necessary. APS cameras also allow three different sized pictures to be shot on the small role of film, from standard prints up to panoramic shots. APS has several drawbacks, however, including the system's incompatibility with 35mm cameras (which means the purchase of a new camera) and the lack of black and white film. However, the APS film itself might be part of the future of 35mm. APS film is made of a polyethylene napthalate base, which is thinner, stronger and hardier than the cellulose triacetate base used in 35mm. Some authorities predict that the base will eventually be used in 35mm film. Whether APS will replace 35mm altogether has yet to be determined.
There are two non-film-based technologies that threaten traditional photography. In the early 1990s, the still video camera was introduced. It combines camcorder and camera, using a floppy disk or an attached computer instead of videotape to record images. The information is stored in analog form. Still video cameras do not produce sharp pictures, no better than a camcorder, but because the images are stored electronically, they can be viewed immediately on a computer screen. There is no photoprocessing involved. Still video cameras have not caught on, though by 1997, digital still video cameras were available that produced sharper images and had more memory available on disk. What might replace film photography all together is digital cameras. Available on the consumer market as earlier as 1994, digital cameras take pictures electronically and store them as computer files, to be edited with computer software such as Adobe's PhotoShop. No photoprocessing is involved. Though the images produced by digital cameras are sharper than still-video cameras, they do not yet match 35mm pictures. As digital cameras improve, they look to be the future of photography in the 21st century.
This is the complete article, containing 1,937 words
(approx. 6 pages at 300 words per page).
