Keep in mind that you can't use a gobo on just any light.
In fact, you basically
have to have an
ellipsoidal, because anything else is so
diffused that putting the gobo in place just doesn't work-- the lines are so badly defined that sometimes it might as well not be there.
Ellipsoidals are the one truly focused, solid, non-diffused (if they're set to be, at least..) light type, and more importantly ellipsoidals *tend* to have an open paperthin slot to put in gobos right up next to the light bulb. (I'm not quite sure how you could make that work on the other types.. esp. not fresnels..) The slot is important because you're going to put the gobo anywhere, it needs to be right up next to the bulb or it won't be as clearly defined.
back to theatre lighting terminology