Movie Making Manual/Cinematography/Crew
Director of Photography 
The Director of Photography (or DP) is in charge of the actual image of a film project. They direct the camera/grip/lighting crews as to how the lights should be placed, how the camera should be exposed, and basically anything related to the film image. They will also choose the film stock and processing for the film. Many times the DP will be present during color timing as well. The DP works very closely with the Director to realize his vision of how the film should look.
Camera Operator 
The Camera Operator does just that - operates the camera. Many times the DP of a film will also operate on a one camera shoot. In some countries, however, the DP is not allowed to operate the camera, thus the need for a camera operator.
First Assistant Camera 
The first assistant Cameraman (or 1st AC) is in charge of the actual camera and related equipment. He/She must always stay with the camera. The 1st AC is also known as the focus puller. The 1st AC's job includes working with the DP and Camera Operator to choose the equipment to be used on the production, unpacking and setting up the camera and related equipment, setting the T-stop, shutter, camera speed, checking the lense, pulling focus, giving the 2nd AC footage readings from the camera at each take, as well as many other camera related jobs.
Second Assistant Camera 
This person writes the info given to them by the script supervisor then slates it when camera and sound are rolling. Between shots they load 35mm film or put it away. This is an entry level position, often internship.