Is there anyway that using after affects can eliminate everything but the light source from my film.
If you're new, you could be talking about video you shot, or animation of lights in 3D space in an AE comp. I, for one, am not certain which it is from your description... and you could also mean something entirely different.
Since you've obviously begun work on this problem, can you clarify what you're trying to accomplish with before and after screen shots?
so my project is about the artificial light on a site, that we have been given. i have started to create almost a walk through of the site which all you see is the light source. i held the camera at eye level and recorded what i saw when i explored.
I now have this film which is taken at night and the light is prominent compared to the architecture. I would like to have, once i have worked out how to do it, a new film that all you see is the light not the architecture, so yes in a way it will be a film of lights in a 3D space. i hope that makes sense now.
Sounds like you need to learn how to use masks and paint tools in AE, possibly also tracking techniques. Not impossible, but not something you will learn on a lazy afternoon, either. Rotoscoping still requires a lot of patience and manual work...