Ross is the name of a succession of London-based lens designers and their company.
Andrew Ross (1798–1859) founded his company in 1830, from 1840 he began producing camera lenses signed "A. Ross". During Andrew Ross's lifetime, the company was one of the foremost lens manufacturers. After Andrew's death in 1859 his son-in-law John Henry Dallmeyer left the firm to establish his own optical company in 1860 and the company was run by Ross's son, Thomas, and became known as Ross & Co. By the 1890s was also making Zeiss and Goerz lenses under licence for sale in the UK and the British Empire. Ross patented a Wide Angle lens design and Zeiss took this further to produce their EWA Protars, before World War 1 Ross and Zeiss worked quite closely together, but at the outbreak of War the British Government put Ross in control of the newly opened Carl Zeiss binocular and optical factory in Mill Hill, London.
A 1902 Ross advertisements includes:
Ross' Symmetrical Anastigmats,
Zeiss' New Planar and Unar lenses,
Zeiss' Convertible Anastigmats,
Goerz' Double Anastigmats, etc.
Ross also made some cameras from about 1855 to the late 1930s. A range of Ross Standard Reflex cameras is listed with an illustration in the 1935 British Journal Photographic Almanac, the sizes ranged from 3½ x 2½ up to Half Plate.
In the mid-20th century, Ross continued to produce lenses, as well as binoculars, epidiascopes, etc. They had begun supplying lenses for Ensign cameras in the 1930s and after World War II Ross merged with Barnet Ensign, and the company later became Ross Ensign, lenses were also made for other companies such as MPP.
Wilkinson, Matthew, and Colin Glanfield. A lens collector's vade mecum. (CD publication) "Version 7/5/2001" (7 May 2001).
British Journal Photographic Almanac 1935, Henry Greenwood & Co 1935