Milanese maker of optical instruments. His few known surviving telescopes and microscopes show him to be an innovative manufacturer of good-quality products. In any event, his reputation certainly extended beyond the Duchy of Milan, as two English manufacturers, James Mann (c. 1685-1750) and his successor Samuel Johnson (1724-72), invited the public to compare their telescopes with those built by the "celebrated Pietro Patroni of Milan." One of his most noteworthy contributions was a focusing technology that made him one of the pioneers of 18th-C microscope-making.