This is the "late" version of the Nikon Series E 50mm f/1.8, distinguished by the chrome ring around the barrel (earlier versions were all black). Despite being marketed as an entry-level lens to accompany the Nikon EM and FE cameras, this "pancake" lens is a cult favorite. It is extremely compact, nearly flush with the camera body, making it the perfect choice for street photography where you want to keep a low profile.