The influence of a redundant camera system for estimation of 3D object position and orientation in a manipulator´s workspace is analysed. The paper analyses the accuracy that can be achieved using a trinocular stereo system, that only has been qualiatively calibrated.  By using stereo combined with a third camera a significant improvment in accuracy is achieved. An experimental system, which exploits colour and Hough transform for object pose estimation, is used for empirical assessment of accuracy in the context of object grasping.