History of the photograph Niepces heliograph

In 1727, the German physician, Johann Heinrich Schulze (1687-744) discovered that light darkens silver salts, the key to creating permanent photographic images, but he did not realize the significance of his discovery. The first permanent photograph from nature was taken by the Frenchman Joseph Nicephore Niepce (1765-1833). In summer 1826, using a camera obscura, he projected an image of the view from his country house in Le Gras onto a pewter plate coated with a light-sensitive solution of bitumen of Judea. Bitumen gradually hardens on exposure to light and, after about 8 hours, the unexposed parts can be washed away to reveal an image. Niepce brought his photograph to London and presented an account of his process, which he called Heliography, to the Royal Society, but his invention failed to produce any interest.

Disappointed, Niepce returned to France leaving his heliograph in the house of his host Francis Bauer, where it laid, stored away and forgotten, until 1952, when it was discovered by a photographic historian Helmut Gemsheim (1913-1995). Gernsheim verified its authenticity and obtained it for his collection which is now exhibited in the Harry Ransom Center at the University of Texas. It is kept sealed in an atmosphere of inert gas, and must be viewed in a darkened environment under controlled lighting.

The picture on the upper left hand side of p. 292 shows a gelatine silver print of Niepce's photograph made in 1952 at the Kodak Research Laboratory in Harrow. It is a precise copy of the original, to the extent that the texture and the unevenness

Reproduction of Joseph Nicéphore Niépce's 'View from the window at Le Gras'.

The same reproduction touched up with watercolours by Helmut Gersheim.

Reproduction of Joseph Nicéphore Niépce's 'View from the window at Le Gras'.

The same reproduction touched up with watercolours by Helmut Gersheim.

Images courtesy of Harry Ransom Centre.

of the pewter plate is clearly visible. Gersheim was unhappy with it and did not allow its reproduction until 1977. The picture on the right hand side shows the Kodak print touched up by Gernsheim himself using watercolours. On the left of this print is the upper left of the family home; beside it a pear tree with a patch of sky showing through an opening in the branches. At the centre we see the slanting roof of a barn with another wing of the family house on the right.

Daguerreotypes

Louis Daguerre (1787-1851), a French painter who had also been experimenting with photography, worked in partnership with Niepce from 1929 until his death in 1833. Daguerre went on to discover that the exposure of a copper plate coated with silver iodide creates a latent image, which can be developed by exposure to mercury vapour, and then fixed using a solution of common

salt. The result is a negative from which copies may be made. This was the birth of practical photography. In 1839, 'daguerreotypes', as they were known, were shown at a joint meeting of the Académie des Sciences and the Académic des-Beaux Arts in Paris by the distinguished L'ateiier de l'artiste. Daguerre 1837. astronomer and physicist,

Francois Jean Dominique

Arago (1786-1853).

Over the next forty years, the quality of photographs improved very significantly. Astronomers rapidly took advantage of the technique. The first daguerreotype of the moon was made in 1840 and of the star Vega in 1850. Astronomical exposure times were long because of the low light levels but the development of more sensitive plates did a great deal to improve the situation.

In 1879, George Eastman (1854-1932), a junior bank clerk and dedicated amateur photographer, was awarded his first patent for coating dry plates with photographic emulsion. The following year he went into the commercial production of dry plates, and the Eastman Dry Plate Company, based in Rochester, New York, was founded in January 1881, with financial help from businessman Henry A. Strong. A major step forward came with the development and patenting (in 1885) of the rolled paper holder by Eastman and William Walker. This was a cassette containing rolled paper film, which could be attached to the back of almost all commercially available plate cameras, in place of the plate holder. Eastman's dry emulsion plates were extensively used in astronomy; in 1880, the American physician and amateur astronomer, Henry Draper (1837-1882) photographed the Orion nebula, a diffuse patch of light in the sword of the Hunter in the constellation Orion. The nebula is just visible to the unaided eye.

Kodak camera

The launch of the Kodak camera in 1888 opened photography to the general public. The camera, containing a 100-exposure film, was priced at $25. After use, the entire camera was returned to the factory, where the film was developed. Photographs and camera (complete with new film) were dispatched to the client, at a cost of $10. The slogan was: "You press the button, we do the rest". Transparent film, made from cellulite, replaced paper film in 1889.

The 'Box 'Brownie\ In 1900, Eastman marketed a cheap portable camera. The body was a simple box and the film cassette could be removed for processing. The camera, named the Brownie, sold for $1 and the film for 15 cents.

The Kodak camera and the Brownie established the name of Kodak in the annals of photographic history.

Colour photography

James Clerk Maxwell (1831-1879) did not confine himself to the theory of light and electromagnetic radiation to be described in the next chapter. He had a practical interest in the formation of colours and demonstrated a system of colour photography in the 1860s. He made three separate black and white images of a tartan ribbon, using blue, green and red filters. The colours of the object were re-created by illumi-Image of tartan ribbon by nating each black and white James Clerk Maxwell. image with light passed through

Box Brownie. Courtesy of Lynn Mooney.

the appropriate filter and projected onto a screen. This was the first example of what is referred to as additive synthesis, building up a coloured image by adding appropriate amounts of coloured light.

Practical colour photography first made its appearance in France in 1904 when the Lumière brothers, Auguste and Louis, presented their Autochrome process to the French Académie des Sciences. It was launched onto the market in 1907. Basically, it combined filters and light sensitive emulsion on a single plate. The filters were tiny grains of starch, dyed and spread over a glass plate, which was then coated with transparent emulsion. After exposure, the plates were processed to produce a transparent image (slide), which was viewed in transmitted light. As with Maxwell's more rudimentary process, the photographic image was created by addition, and could be viewed only in projection. Autochrome plates were popular as they could be used in existing cameras, although exposure times were long (at least a second, even in bright sunlight compared to less than 0.1 seconds for black and white film).

It was the Eastman-Kodak Company, once again, which brought colour photography to the general public in 1935, when it launched Kodachrome, the first colour negative film. These films are layered with three different emulsions. Each one is sensitive to a different primary colour and a 'colour coupler' is introduced, during development, to deposit an appropriate dye in areas where silver forms. This film may be used for prints or projection (slides).

Digital photography

Digital imaging has almost completely replaced imaging based on chemical changes in light sensitive films. In digital cameras, images are recorded using electronic image sensors (pixels) arranged in a grid, rather like the retina of the eye. Light striking individual sensors during an exposure is converted to electrons (photoelectric effect, see Chapter 13) which are registered as electrical signals. After the exposure, the signals are stored in a memory chip and the camera is ready for the next exposure.

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