1792 - Johann Heinrich August Duncker (1767-1843) began to make optical instruments in Rathenow;

1819 - Duncker's son Eduard (1797-1878) took over the company and began making auricular tubes, then latter expanding to become a successful European manufacturer of spectacles and frames;

1845 - having no children Eduard passed the business on to his nephew Emil Busch (1820-1888) as Optische Industrie-Anstalt, Rathenow;

1852 - Busch began the manufacture of cameras;

1865 - began manufacture of the wide angle Pantoscop lens;

1872 - the Optische Anstalt Rathenow became the stock market company Emil Busch AG; worked closely with Zeiss, from which they obtained their optical glass;

1908 - company was renamed Emil Busch AG Optische Industrie; from around the same time Busch products were badged ROJA (Rathanower Optische Institute) or Roia;

1929 - Zeiss became a majority share holder and Busch ceased making lenses, but continued making cameras;

1930s - Busch developed the standard 10 x 80, 45 degree offset, binocular used widely in the second world war;

1946 - company became the state-owned Rathenower Optische Werke GmbH and from 1948 VEB Rathenower Optische Werke (ROW), later becoming part of VEB Carl Zeiss Jena.