A short excerpt from the fourth chapter: Busch
… In around 1850 Busch enlarged the factory to increase mass production (12,13). In 1861 Busch presented his optical production at London World Fair. The growth in production brought the work force to 130 in 1851. Besides new spectacles, binoculars and other optical items, from 1852 the company began producing photographic lenses similar to Petzval's, of high luminosity and quality that the market required for the large plates that followed the invention of the collodion process. From 1857 the chemical focus difference of Petzval lenses, for the first time in Germany, was corrected (15). In 1857 they made a Petzval with a front lens that had a seven-inch diameter (7 Zoll) and later an even larger one that measured ten-inch (10 Zoll). The focal length was about 86cm and covered a 76x76cm format. In 1867 the lens met with enormous success at the International Photographic Exhibition where it was nick named the "Mammoth Lens" (7). In 1865 Busch designed and built his most famous lens, the Pantoskop, a significantly corrected 100° wide-angle lens. Busch's production was geared toward the middle to high market with prices that were much lower than his rival Voigtlander's, from one-third to one-half less...
(7) R. J.W. Fowler. Brit. Jour. 1867, XIV, 366.
(12 ) Cassell's Cyclopaedia of Photography, New York: Arno Press, 1974, pp. 390-391.
(13) Encyclopedia of Nineteenth-Century Photography, Vol. I New York: Routledge/Taylor & Francis Group LLC, 2008, pp. 231-232.
(15) Grabenhorst Carsten. Voigtländer & Sohn. Appelhans Verlag, Braunschweig, 2002. pp. 56-57.