Rear Projection Setup

I have seen a church allot 30 feet behind the projection screen for a rear projection setup. this is unnecessary all you need is a mirror. There are two setups that can be used, project from below up to the mirror and from just below the screen at the mirror. The setups are diagrammed below:

Projector located below the mirror.

Projector located just behind the screen.

Now about the screen.  As you may know a glass bead screen is by far the best screen.  After that a white sheet also works.  In forward projection setups you can use reflective white paint or regular white paint as well.