German maker of astronomical instruments who introduced the meridian, or transit, circle, a specially designed telescope for measuring both the time when a celestial body is directly over the meridian (the longitude of the instrument) and the angle of the body at meridian passage. By 1796 he was engaged in the construction of a dividing engine, a machine used to mark off equal intervals accurately, usually on precision instruments. In 1804 he was one of the founders of an instrument-making business in Munich, and in 1809 he helped establish at Benediktbeuern an optical works that was later moved to Munich.

In 1819 he built for the German astronomer Friedrich Bessel a transit circle, combining the transit, an instrument used for determining longitude and time, with the mural circle, an instrument mounted on a wall for zenith measurement. This combination had been introduced earlier but had not been adopted. Reichenbach's form of the instrument came into general use.