Camera rotating around rolling rigidbody sphere

I have a camera linked to a rigidbody sphere parent that's rolling down a spiralling tunnel. The camera is presently rotating wildly (because the rigidbody sphere is) - what script(s) could I use to make the camera ignore the local rigidbody rotation down the spiral? I don't want to control the camera or sphere by mouse or keyboard input.

Connect the camera to a new GameObject and add to this gameobject a script with:

var follow : Transform;

function LateUpdate() {
    transform.position = follow.position;

next, in inspector of the gameobject, set `follow` to the rolling rigidbody instance (just drag it from scene view to this property).

that “Empty GameObject Trick” is like this…

var targ:Transform;
var offset:Vector3;
function Start(){
offset=transform.position-targ.position;//init offset at start
function Update(){