The first photograph is considered to be an image produced in 1826 by the French inventor Nicéphore Niépce on a polished pewter plate covered with a petroleum derivative called bitumen of Judea. It was produced with a camera, and required an eight hour exposure in bright sunshine. However this process turned out to be a dead end and Niépce began experimenting with silver compounds based on a Johann Heinrich Schultz discovery in 1724 that a silver and chalk mixture darkens when exposed to light.
Niépce, in Chalon-sur-Saône, and the artist Louis Daguerre, in Paris, refined the existing silver process in a partnership. In 1833 Niépce died of a stroke, leaving his notes to Daguerre. While he had no scientific background, Daguerre made two pivotal contributions to the process.
He discovered that by exposing the silver first to iodine vapour, before exposure to light, and then to mercury fumes after the photograph was taken, a latent image could be formed and made visible. By then bathing the plate in a salt bath the image could be fixed.
In 1839 Daguerre announced that he had invented a process using silver on a copper plate called the Daguerreotype. The French government bought the patent and immediately made it public domain.
Across the English Channel, William Fox Talbot had earlier discovered another means to fix a silver process image but had kept it secret. After reading about Daguerre’s invention Talbot refined his process, so that it might be fast enough to take photographs of people as Daguerre had done and by 1840 he had invented the calotype process. He coated paper sheets with silver chloride to create an intermediate negative image. Unlike a daguerreotype a calotype negative could be used to reproduce positive prints, like most chemical films do today. Talbot patented this process which greatly limited its adoption.
The Daguerreotype proved popular in responding to the demand for portraiture emerging from the middle classes during the Industrial Revolution. This demand, which could not be met in volume and in cost by oil painting, may well have been the push for the development of photography.
In 1884 George Eastman, of Rochester, New York, developed dry gel on paper, or film, to replace the photographic plate so that a photographer no longer needed to carry boxes of plates and toxic chemicals around. In July of 1888 Eastman’s Kodak camera went on the market with the slogan “You press the button, we do the rest”. Now anyone could take a photograph and leave the complex parts of the process to others. Photography became available for the mass-market in 1901 with the introduction of Kodak Brownie.
Colour film became standard, as well as automatic focus and automatic exposure. Digital recording of images is now the standard, as digital cameras allow instant previews on LCD screens and the resolution of top of the range models has exceeded high quality 35mm film while lower resolution models have become affordable. For the enthusiast photographer processing black and white film little has changed since the introduction of the 35mm film Leica camera in 1925.