Grab yourself a GStar-EX camera from
here
If you're looking to tracking asteroids, these types of low light video cameras are your best option. Many amateurs use them in conjunction with their telescopes either piggybacked (with a good telephoto lens attached) or through the scope at the prime focus.
If your pockets can extend a little, another way is to invest in a large telephoto lens (2000mm is not out of the question) attached to the camera and mounted on an alt-az tracking mount.
Your main concern, apart from light gathering capability (which means a large aperture), is field of view. Tracking asteroids requires a scope or lens with a good field of view, which usually means it has to have a reasonably fast F ratio...the faster (smaller number), the better. That way, you cover a larger area of sky and have a better chance of finding and tracking an asteroid. It also means that images will be gathered quicker as well (no need to go into the optical details, just yet), and as I mentioned before a large aperture will allow you to gather more light, therefore you'll see fainter objects. In any case, the importance of the field of view is paramount. Asteroids, especially NEO's and other co-orbitals, move quickly so a small field of view is virtually useless. Makes it too hard to find, initially, and then track the objects.
Hopefully, I've been of help. There's plenty of us here that are willing to help
