Noia............I think that you are perfectly correct!!! I do recall the earlier days (about last Tuesday ) when you had to do something like that to project stuff onto a wall/screen? This is way before the days of modern data projectors...it was a bit like an overhead projector that did slides? but this projected the screen.......only because of the simple lenses it would be upside down?

I will have to check that on some of my older kit


Thanks folks...nice thread.