 For the calculations, 8 artillery gunners and 3 corporals were made available to Petzval by Archduke Louis of Austria (commander of the artillery), since the artillery was one of the few professions where mathematical calculations were made.By 1845 Petzval's collaboration with Voigtländer, who held the license to produce the lenses, had become "mired in disputes'.Voigtländer moved production outside of Austria and therefore beyond Petzval’s patent limitations.