If you have multiple stereoscopic cameras in your scene, you may want to link each camera with a different set of objects. This feature is most useful when you want to have different stereo settings for different objects. This scenario occurs in stereo setup because one set of stereo parameters may not produce a visually pleasing stereoscopic image for the whole scene. For example, if you have a multi-camera rig, you can associate each layer in the rig with a different set of objects.
To link a camera to selected objects
The camera and the objects are linked as a set.
To break links between a camera and objects