Pierre Petit, nicknamed "Collodion le chevelu" because of his large head of hair, apprenticed with André Disdéri (1819-1889), inventor of the carte-de-visite (visiting card).
He was the photographer for the Universal Exhibition of 1855, 1867, and again in 1878. In 1858, he opened his own studio at 31 Place Cadet (Paris, 9th arrondissement) and in 1959 made a book devoted to the French episcopate.
A series of portraits of contemporary men of letters and artists in 1860 prefigured the Galerie des Hommes du Jour, published the following year with biographical notes. From 1871 to 1886, he was asked to photograph the different stages in the construction of the Statue of Liberty in New York. His son continued his work after his death.