Sigma Corporation is a Japanese company, manufacturing cameras, lenses, flashes and other photographic accessories. All Sigma products are produced in the company's own Aizu factory in Bandai, Fukushima, Japan. Although Sigma produces several camera models, the company is best known for producing lenses and other accessories that are compatible with the cameras produced by other companies.

The company was founded in 1961 by Michihiro Yamaki, who was Sigma's CEO until his death at age 78 in 2012. Sigma produces products to work with cameras from Canon, Nikon, Pentax, Sony, Olympus and Panasonic, as well as for their own cameras.