One of the important image and video registration goals is the accurate motion and structure estimation. On the other hand, a good motion estimation is also an important requirement for most mosaicing and novel view generation techniques. While it has been well known for a while that narrow field-of-view cameras have a hard time distinguishing between certain kinds of rotations and translations, it has been recently observed that using omni-directional cameras significantly decrease those ambiguities. In this paper we study the relationship between field of view and the amount of motion uncertainty. To this goal, we derive an analytic formula for the Fisher information matrix involved in the motion estimation task. We use this to examine the coupling between the different motion parameters and the relation between those uncertainties to the camera filed of view. In particular, we provide a formal proof to the previously observed phenomena, that for full 360o omni-directional cameras there is *no correlation* between rotation and translation parameters estimate.