Sangamo Weston was a company that made light meters, among much other electrical equipment. It is particularly known for the Weston Master series of selenium meters.

Weston was founded by chemist Edward Weston, who held many patents for electrical inventions, from permanent magnets through cellulose manufacturing, dynamos, arc & filament lights and the magnetic-drag speedometer to electrical measurement instruments (and even US 895218 - a fruit box!)[1] Weston's son, Edward Faraday Weston, applied for a U.S. patent on the first Weston Exposure meter, granted as No.2016469 in October 1935.[2] This was a cylindrical case with an electrical meter at one end, and an iris at the other; an adjustable scale around the meter opened and closed the iris, and showed the exposure. Sangamo was originally "Sangamo Electric Co.", in Springfield, Illinois, and set up a British subsidiary in 1921. Sangamo acquired the Weston Electrical Instrument Co. in 1936. [3] Since Weston were an early player in the light meter game - before film speeds were standardised, Weston had their own film speed scales.

At some point, Weston products were distributed by Ilford in the UK. The company was bought out by Schlumberger in 1976, but still exists making electrical timers.

The EuroMaster light meter is now being made by a company called Megatron.

  1. Edward Weston page on wikipedia
  2. Letter from Weston employee and the Western Photographic Historical Society Photographica Digest, vol.XII no.12 has an article on the Westons and a copy of the patent. See also Google Patents: US 2016469 Exposure Meter
  3. Sangamo History