full-time. By 1861 Zeiss was considered to be among the best scientific instruments in Germany with about 20 people working under him with his business still growing. By 1866 the Zeiss workshop sold their 1,000th microscope. In 1872 physicist Ernst Abbe joined Zeiss and along with Otto Schott designed greatly improve lenses for the optical instruments they were producing. After Carl Zeiss's death in 1888, the business was incorporated as the Carl-Zeiss-Stiftung in 1889.
By World War I, Zeiss was the world's largest location of camera production. Zeiss Ikon represented a significant part of the production along with dozens of other brands and factories, and also had major works at Dresden.
In 1928 Hensoldt AG was acquired by Carl Zeiss and has produced the Zeiss binoculars and riflescopes since 1964.,occasionally resulting in twin products being offered under both the Hensoldt and Zeiss brand names. The Hensoldt System Technology division (resulting from a merger of the military optics operations of Leica and Hensoldt) was continued by Zeiss under the Hensoldt name until 2006.
As part of Nazi Germany Zwangsarbeiter program, Zeiss used forced labour during the Second World War. The destruction of the war caused many companies to divide into smaller subcompanies and others to merge together.