Black Horseman in Front of a Doorway, c. 1855. The genre of equestrian portraiture dates back to classical antiquity, but translating it to photography was tricky because of the long exposures required by the early processes. Nadar?s example evokes conventions of studio portraiture, employing a large painted backdrop to disguise the actual location, which was probably outdoors. In the slightly earlier work below, the uniformed rider appears to be guarding the gate. Comparing the prints provides an opportunity to contrast the graininess and softness of the earlier salted paper process with its successor, the more finely detailed albumen print made from a glass-plate negative.