Most movie people know the basic function of a film's director, but what about the director of photography? It's an oft-ignored position, but the DP often has as much to do with the look and feel of a movie as the director. Here is a brief guide to the functions of a director of photography.

Lighting. One of the most important duties a director of photography has is to light the set in accordance with the director's vision for the scene. Some famous cinematographers (another word for the director of photography) are known for their distinctive lighting styles-most notably Gordon Willis, who is well-known for his dark compositions in movies such as "The Godfather" and "All The President's Men", earning him the nickname "The Prince of Darkness."

Framing. The positioning of actors and the set within the frame is also within the domain of the director of photography. Have you ever been watching a movie and noticed a visible boom mic at the top of the shot? That means the director of photography messed up, or that the filmmaker is making a meta-textual comment about how cinema makes us voyeurs. But it was probably just a mistake.

Selecting film stock. Here's where things start to get technical. One of the other duties of the cinematographer is the selection of what type of film stock to use when shooting the movie (super 8, 35mm, etc.) in order to best capture what the director is looking for. For example, if a movie is going to be a gritty, realistic war movie, something with a little bit of grain might be appropriate.

Moving the camera. This doesn't mean that the cinematographer necessarily operates the camera him or herself (although this does happen sometimes), but that he or she often makes the decisions about where to put the camera and where to move it over the course of the scene. In the early days of cinema,  cinematographer Karl Freund (who went on to become a notable director himself) became famous for his amazing tracking shots for directors like FW Murnau.