True, just a little typo on my part. I was thinking to myself about the light leaving the lens in which most cases involves two refraction points from two plaino convex lenses. That however clearly didn't come out that way in my description.
Another need for it (although probably not what you were looking for) still involves the flare. Our current national tour, To Kill a Mockingbird, deals with a lot of rear projection onto the back walls. During the jail scene, we are projecting Tom's head inside of a jail cell onto the back wall. We are using a Source 4 19º EHD barrel. The gobo itself looked great and dropping in the donut did not enhance the gobo at all. However, there was still a bit of flare that allowed us to see Tom's entire body step into the light. The donut eliminated that completely while the gobo itself went unchanged.
