The optical principles of a pinhole camera have been known for a long time. In the 5th century B.C, Mo Ti noted in China that light passing through a pinhole created an inverted but otherwise exact image. Aristotle noted similar effects in the following century. In the 10th century AD, Arabian scholar Ibn Al-Haitham (Alhazen) added the observation that an image was formed sharply through a smaller aperture and that the image got diffuse with increasing apertures.

There were painters long before there were photographers. Portaits and architectural details were sketched, etched or painted before photography was invented. Between the 17th century and the 19th century, there was a growing need to accurately record details and control perspective in the representation of landscapes and sceneries. The exact origin of the camera obscura is not known but it is evident from literature that such a device was familiar to scientists, magicians and artists by the mid 16th century. A painter employed the camera obscura, which was essentially a large room with a small hole on one of its walls, to trace an image of a facing landscape that was projected on its opposite inner wall. This evolved into the camera lucida which employed a prism and a lens to project a distant image onto a tracing paper. However, the project images were ephemeral and artists and scientists were constantly looking for a way to "freeze the world around the viewer".

The Birth of Photography

In the year 1725, Johann Heinrich Schulze, professor of medicine at the University of Altdorf, accidentally discovered that silver nitrate darkened on exposure to sunlight. He also determined that the effect was caused by light, not heat. By the mid-18th century, Swedish chemist Carl Wilhelm Scheele and Italian Giacomo Battista Beccaria published experimental results of light's reaction on silver chloride. Later, in 1782, the chief librarian of Geneva, Jean Senebier, experimented with the reaction of silver chloride with varying portions of the light spectrum. These would later prove to be seminal research work leading to the invention of the photographic film.

Among the many people striving to find a photographic medium to record an image was frenchman Joseph Nicephore Niepce. In the 1820s, he worked on a heliograph and is credited with the first recorded photographic image made in 1827 entitled "View from His Window at Le Gras". However, when his research reached a stand still, he teamed up with Louis Jacques Mande Daguerre. Daguerre was a painter by profession and at that time was painting backgrounds as a stage designer. He had used the camera obscura to achieve perspective effects on large scrims and easels and at some point, wanted to make the projected images permanent. Upon Niepce's death in 1833, Daguerre perfected the technique to record images and called his invention, the daguerrotype. By exposing a silver coated copper plate, sensitized in iodine vapor, and later developing its latent image by fuming in mercury vapor, a monochromatic, laterally reversed, unduplicatable picture was formed on the plate. He offered to sell his process in 1838 and when this attempt failed, he marketed it differently in 1839, as a cheap and inexpensive means of making portrait images. The french government officially announced his invention on August 19, 1839.

Around the same time Daguerre was perfecting his invention, in London, William Henry Fox Talbot was working on his invention of the photographic paper negative. Originally called photogenic drawing that later evolved into a calotype or talbotype, the negative was monochromatic, spatially and tonally reversed. When placed in contact with a chemically treated surface and exposed to sunlight, an image was born from the negative, that had spatial and tonal values restored. In contrast with a daguerrotype, multiple prints could be made from a negative. Talbot made his first prints around 1835 but didn't consider them important enough to announce until 1839 when Daguerre's invention was announced. Hercules Florence, a French-born artist coined and first used the work photography to describe his method of producing images of drawings. Herchel would later persuade Talbot to use the term photography instead of photogenic drawing .

Daguerre was a shrewd businessman, always trying to find ways to franchise and market his invention to make money. Talbot on the other hand was more interested in locking up his invention by patenting his process. Neither of these inventions would have been possible without John Herschel's selfless dissemination of his research findings to Daguerre and Talbot. In 1819, he discovered how to stabilize the chemicals on a photographic medium so that they no longer continued to react to light even after an exposure. Hypo - hyposulphite of soda or sodium thiosulphate continues to be used today in film processing.

Daguerrotype was franchised and hence was gaining popularity over the calotype, despite the latter's ability to product multiple prints of an image. Within two years, cameras were being manufactured in Europe and the United States and achromatic lenses were becoming available. Being expensive, it was slow to reach the middle-class, making inroads mostly in the industrialized countries such as France, England and the United States. Both the daguerrotype and the calotype required long exposure times, of the order of 5 to 60 minutes depending upon color and light, which was too long to hold a portrait subject still. In addition, the calotype suffered from a lack of image definition (because of the grainy paper texture) and problems with fading. The next series of innovations addressed these problems in particular.

The Colloidon Era

In the early days, it was not much fun to have a portrait taken. Since the exposure times were very long, the subject's head was usually clamped to prevent any movement, typically causing grim facial expressions in the subject. Viennese scientist Josef Max Petzval's invention of a lens that admitted more than 20 times the amount of light admitted by contemporary lenses, caused a substantial reduction in the exposure times. This invention, coupled with the use of sensitized colloidon plates reduced exposure times to a mere 5-8 seconds. The wet colloidon method was invented in 1850 by the english engraver Scott Archer and he gifted the process to the public.

The colloidon process resulted in images with a crisp definition and strong contrast. Since paper negatives were grainy, glass plates were used instead, which increased the acceptance of calotype portraiture. In 1847, albumen was used as a binder for silver salts on a glass plate and albumen prints, paper coated with albumen and silver salts, evolved around the same time. These prints were long lasting for upto 30 years. In the 1860s, Autotype, a carbon-based printing process, gained a following due to its rich, deep tonalities as well as a resistance to fading. John Herschel's discovery of light sensitivity of Platinum Chloride led to an expensive platinum paper that had long tonal scale and permanence of prints.

The wet colloidon process involved "a derivate of guncotton that became liquid transparent and sticky when immersed in alcohol." By pouring the liquid colloidon mixed with Potassium Iodide (and later, Potassium Bromide) on a glass plate and immersing the plate in a Silver Nitrate bath to produce Silver Iodide, exposure times were reduced considerably. However, the plate had to be used in its wet state and also had to be developed while still moist. This necessitated the use of portable darkrooms and was cumbersome to carry for outdoor work. Dry colloidon plates were invented in 1860 by French scientist Dr.J.M.Taupenot but its use was not practical (too slow) until 1883 when celluloid could be manufactured in standard thicknesses and coated with a Silver Bromide emulsion.

At first, Silver Bromide gelatin emulsion was coated on celluloid and backed with paper. The emulsion had to be stripped off the paper, transferred to glass then developed and printed. Soon, roll film format evolved, originally conceived in 1854 by the British inventor Arthur James Melhuish, where the exposure could be directly made on the paper backed emulsion. Eastman company commercially produced the rollfilm in 1888 and by 1895, it was produced in a form that could be loaded in daylight.

While technical improvements reduced exposure times, it was still slow enough that lenscaps could be used as shutters on lenses. Simply removing a lenscap started an exposure and the cap was replaced when the exposure was to be stopped. Exposure meters were not yet practical during this era because different photographers sensitized the plates differently and exposed based on experience. Only when standardized emulsions were practical in the 1880s was there a need to relate the amount of light to film sensitivity. The earliest exposure meters were similar to slide-rules, calibrated for various months and times of the day, and marketed for 13 different latitudes. Such a meter was designed and patented in 1888 by Charles Driffield and Ferdinand Hurter. Tripods were used from the early days for stabilizing a camera although, at that time, it was essentially a rotating pedestal on which a camera was placed.

Photojournalism emerged as a new way of telling a story. The first recorded picture story was that of Alexander Gardner who, in 1865, documented the hanging of the Lincoln conspirators. A series of seven pictures described preparations for and the hanging of the 4 conspirators who assasinated Abraham Lincoln. In addition, pictures of the four conspirators and the generals who captured them, were made prior to the hanging. While industrialization had not yet made it possible to print images in publications, that was certainly where photography was headed. For a start, "The Pencil of Nature" was the first magazine, issued between 1844 and 1846, to explain and illustrate scientific and practical applications of photography.

Despite the rapid technological strides made in this era, there was still a constant desire to improve film's sensitivity to light, for sharper images and for images in full color.

Photography in the early 20th Century

Portrait photography dictated innovations in the 19th century but now the focus was turning to journalism, particularly regarding a coverage of the world wars. There was also a growing obsession with industrialization which, until the great depression of the 1930s, was a key photographic subject. Images were used for advertisement and publication in trade journals.

The period between the two world wars was also rich in photographic experimentation. Talbot's photogenic drawing technique (of placing objects directly on light sensitive paper) was back in vogue. These were essentially cameraless images. Photographers experimented with new techniques such as collages, montages and multiple exposures. All the experimentation rejuvinated an interest in straight photography. This time, the focus was on finding new vantage points and exploring reflections and abstracts along with extreme close-ups.

Journalism led to the invention of equipment that could be hand-held and easily ported. An early model of an SLR was patented by Thomas Sutton in 1861 but the most influential SLR model was introduced by Folmer and Schwing, named Graflex, around 1900. It had a cubic design with bellows extension and a 4-sided hood on top. A mirror had to be inserted at a 45 degree angle to focus a subject on a screen within the hood. Flash photography was invented in the late 19th century, when magnesium wire or powder was burned for its white light. By 1925, German Paul Vierkotter invented a flashbulb that encased magnesium wire in glass, making it smoke free. After 1950, dry cell battery powered electronic circuitry resulted in lighter and faster portable flash units. By 1963, the Kodak Brownie camera, introduced in 1900 as a fixed-focus simplistic camera for amateurs, was revised into the Kodak Instamatic camera that contained a built-in popup flash.

Lens quality was undergoing constant improvements as well. In the early 1890s, the German firms of Carl Zeiss and Carl Goerz introduced an anastigmat lens that resolved both vertical and horizontal planar distortions. Wide angle lenses were designed by American Charles E. Harrison and have been used since 1860. The first telephoto lens was patented in 1891 by Thomas Rudolf Dallmeyer.

Improvements in film and lens technology drove the need for accurate and faster shutters. In the late 1880s, Carl Paul Goerz designed a sector shutter that had a set of metal blades called a diaphragm. In 1904, Friedrich Deckel invented a compound shutter that controlled both the aperture and shutter speed and was enclosed in camera bodies. This shutter became a standard on all handheld cameras. Faster shutter speeds were achieved by a focal plane shutter, patented by German photographer Ottomar Anschutz in 1888. It operated in a fashion similar to roller blinds and facilitated speeds up to 1/1000 of a second.

Accurate exposure meters too became a necessity and practical, given the ability to standardize the manufacture of rollfilms. Actinometers improved over the previously available slide-rule type exposure meters. These consisted of a piece of light sensitive paper that turned dark when exposed to light. The first visible number on the paper indicated the required exposure in the available light. However, the most useful meter was the photoelectric meter invented in 1932 based on the light sensitivity of Selenium. The Weston Universal 617 meter had a needle that, when placed between two photoelectric cells, was deflected to indicate the required exposure. These meters were too expensive until the late 1930s when cameras were being manufactured with built-in meters.

Perhaps a major revolution in film technology was the introduction in 1948 of the Polaroid Land 95 camera, designed by Edwin H. Land. Back in 1864, the Dubroni camera tried to sensitize and develop a colloidon plate, all inside the camera. There was an opening at the top of the camera, through which the photographer poured sensitizing and processing chemicals on the plate inside the camera. The polaroid camera was a vast improvement over the Dubroni camera. Tiny packets of processing chemicals were included in the film pack and a system of rollers broke these tiny packets and poured and spread the chemicals evenly over the film. In a minute after exposure, the print was ready. Polaroids were monochromatic until 1962 when the Polacolor film was introduced. Other major developments in films were the introduction of the Kodachrome in 1935, Agfacolor Neu in 1936, Kodacolor roll film in 1941 and the Ektachrome in 1942.

Birth of Color Photography

During the earliest days, dyes and plates wee either too faintly sensitive to color and required long exposures or they were not sensitive to all colors. Photographers regularly hand colored prints made from calotypes. Calotypes also provided an advantage of being able to tint prints in various tones including the popular Sepia. In 1842, Sir John Herschel first described a non-silver based process called the Cyanotype. This process was based on the photosensitivity of Ferric salts which were reduced to a Ferrous state on exposure to light. The prints were blue in color and became popular in the 20th century for duplicating industrial drawings or blueprints . Research was conducted into adding dyes to sensitize film emulsion. In 1873, German photochemist Hermann Wilhelm Vogel developed a process called optical sensitizing, adding dyes to a Silver Bromide emulsion to produce orthochromatic plates. By 1903, a panchromatic film sensitive to all colors was developed.

Developments in color film technology were fueled by early 19th century research into human vision. The discovery of Red, Green and Blue as primary colors from which all other colors were derived, was an important one. In 1907 in Lyon, France, the Lumiere Brothers invented and marketed the Autochrome, a positive glass plate based on the theory of adding colors together on one plate. Around the same time, Heliochrome, a process based on subtractive colors was also developed. This was followed by a series of film emulsions, both in positive and negative forms were introduced by such companies as Kodak, Agfa, Konica and Fuji among others.

Evolution of the Camera

The earliest pinhole camera evolved into a box camera where the front element containing the lens could be adjusted to focus subjects at varying distances. Special camera equipments were manufactured to produce Carte-de-Visite images (where multiple small images were produced on one plate), stereoscopic and panoramic images and other novelty camera that could be concealed for detective work. In 1851, the first bellows focussing system camera was introduced by W and W. H. Lewis in New York. By the 1860s, rising fronts, swinging fronts and backs were available in bellows cameras. In 1857, American artist David A. Woodward patented a solar microscope or magic lantern , a device to make enlarged prints from negatives. George Hare from England designed a flat-bed view camera in 1882. Rollei introduced a twin lens reflex camera in the early 1900s and SLRs and handheld cameras became popular. The introduction of a lightweight 35mm Leica camera, with sharp images, fast film advance and instant exposure, revolutionized the photography industry. The Contax S camera, introduced in 1949 by the East German Zeiss-Ikon company, because the first 35mm SLR to have a pentaprism for eye-level viewing through the lens. Recent trends in camera equipment have included point and shoot cameras, electronics for metering and controlling exposure, powerful flash units, motor drives for fast film advance, APS format and digital technology