Each camera that you create is made up of three separate parts: the camera root, the camera interest, and the camera itself. If you look at a camera in the explorer, you’ll see that the camera root is the parent of both the camera and its interest. Each of these elements is viewable in the 3D views as well.
The camera root is represented by a null in the scene. By default, it appears in the middle of the wireframe camera, but you can translate and animate it as you would any other object. The null is useful as an extra level of control over the camera rig, allowing you to translate and animate the entire rig the same way that you animate its individual components.
The camera is the camera is the camera. In the 3D views, it is represented by a wireframe control object of a camera which is, for rendering purposes, invisible, but it allows you to manipulate the camera in 3D space. The camera has a directional constraint to the camera interest.
The camera’s interest—what the camera is always looking at—is represented by a null in the scene. You can translate and animate the null, as you would any other object, to change the camera’s interest.
The camera icon displays a blue and a green arrow. The blue arrow shows where the camera is “looking”; that is, the direction the lens is facing. The green arrow shows the camera’s up direction. You can change its direction by rolling the camera (press l).
For more information on how to animate a camera roll, see Animating Cameras.
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