Film and Flash Technology

Photograph quality relied as much on the performance of film and the lighting of the subject as on lens technology. In the days of long exposures, professional photographers became proficient at calculating exposure times through trial and error and controlled the light entering the camera merely by removing and replacing a lens cap. Exposure tables, calculators, and strips of photochromatic paper assisted the amateur photographer. Cameras began to incorporate simple mechanical shutters to control light input, and the first leaf shutter, the Deckel, was developed in Germany in 1902. Accurate short exposures only became possible when the photoelectric cell (or photocell) was invented. The first practical photoelectric cell was invented by the German physicists Julius Elster and Hans Friedrich Geitel in 1904. The photoelectric cell was first incorporated in a separate exposure meter in 1931 by the American William Nelson Goodwin Jr. and was developed commercially by the Weston Electrical Instrument Company of Newark, New Jersey, in 1932 as the Photronic Photoelectric Cell. The U.S. Time Corporation (Timex) produced an “electric eye” camera in 1950, but the first camera to feature a built-in photoelectric cell positioned behind the lens was the Pentax Spotmatic, introduced in 1964 by the Japanese Asahi Optical Corporation. Built-in exposure meters meant that cameras could be operated by the selection of foolproof automatic settings. The first automatic-exposure SLR camera was the Pentax ES model of 1971.

From the 1880s, electric lights could be used to enhance indoor lighting, and flash photography was possible through the use of flash powders and magnesium ribbon. Flash photography became easier with the invention of the electric flashbulb, patented by the German inventor Johannes Ostermeier in 1930. The electronic flashbulb was invented in the United States in 1935. Flashbulbs were initially mounted in separate flashguns, but as they became smaller, they were embodied in attachments that fitted directly onto the camera. The hot shoe flashgun attachment, a metal “shoe” on top of the camera into which a metal “foot” on the flash was slid, was introduced in 1939. As cameras became fully electronic, the flash became an integral part of the camera.

In the 1930s, highly flammable celluloid film was replaced by nonflammable cellulose acetate. While the Scottish physicist James Clerk Maxwell expounded the principles of the three-color photographic process in 1861, it was another thirty years before the French doctor Gabriel-Jonas Lippman developed a process for color photography. In the early twentieth century, a number of color processes were developed, including the Lumière brothers’ Autochrome process, but these were for plates rather than film and were time-consuming and expensive. In the 1930s, Eastman Kodak and the German company Agfa (A.G. für Anilin, the Aniline Company) began to develop color film in transparency form. Kodachrome film became available in 35 mm cartridges and roll film in 1936, and Agfacolor film was available in 35 mm cartridges the next year. The first color negative film, Kodacolor, did not come on the market until 1944 and was quickly followed by faster Kodak Ektachrome transparency film until 1946 and negative film in 1947. While Eastman Kodak’s domination of the camera market began to wane when Japanese companies moved into the camera industry in the 1950s, the company continued to be a leading force in film technology.

After the introduction of color film, the main improvements in photographic film lay in the development of faster films. Film speed is a measure of light-sensitivity. The first system for measuring film speed was developed in Britain in 1890, but from 1947, the American Standards Association (ASA) ratings became the industry norm. Eastman Kodak has continued to be a leader in film technology: for example, it launched a series of high-speed X films, starting with Tri-X black-and-white roll film in 1954. A significant advance in 1963 was the development by the Swiss company Ciba-Geigy of the Ultrachrome process, which allowed prints to be made from transparencies.