Design gobo on a spotlight?

[church]

the diagram posted by Derek provides a very visual explanation of my original post. If you place a gobo at the focal point beyond the lens train the light that passes through this point will project a gobo image but there is a significant amount of light that does not pass through this point which can make the image out of focus and may simply wash out the image so it cannot be seen. The diagram shows nicely why the donut works with a gobo because it removes these unwanted light sources -unwanted when using a gobo.

 

[FMEng]

Has no one considered the possibility that his spotlight has a gobo boom in it? I know M2's do, as do some other spots.

Some of the Lycian's do as well. I have put gobos in our model 1238 Super Clubspot and it works great.