I unfortunately never took a class on photonics but this law of Etendue seems to be very relevant to a project I am not even sure is possible. I am trying to create a lamp that does something like these shadow lamps but with a LED smart bulb 
Now I understand that how these work is that the light source is bright and as tiny as possible as to cast these shadows so clearly. If I put this shade on a normal lightbulb it ends up being so blurry you cant see the pattern.
My thought then was to find a combination of a lens with a simple physical filter (pinhole) in order to turn a diffuse light source into a dimmer but focused point light.
I have two main bulbs I could do this with. And I realize that my biggest roadblock is this law. Which in my layman's term is saying that these light sources start as diffuse so you will not be able to make them not diffused.
But this law breaks my intuition. I thought I could focus say the GU10 bulb with a convex lens into roughly a point, put a pinhole right at that point, and functionally get a point light source emanating from that pinhole. That's sorta how cameras work but in reverse anywho right? But this seems to be directly in conflict with the conservation of Etendue. So perhaps I am missing something. Or perhaps the phyiscal filter of a pinhole would "cheat" things my eliminating light rays that aren't going to help create my point light source.
Perhaps making a pinhole through a thicker material is my ticket. Perhaps bouncing that pinhole light on a mirror or two will get the light to behave more in phase?
The problem came when I actually got the bulb and the lens. You can see that there appears to be a fresnel filter on the bulb and although I couldn't picture it you can even get the individual red, green, and blue point lights to sort of focus on a point with the right distance.
But even when I put the lens at a distance that points a point at the wall that same point doesnt seem to cast sharp shadows. At least not sharp enough ones that I can say it mimics a point light source.
I realize this could be an engineering question. What I am more asking is: is my basic understanding of Etendue correct? Is getting these bulbs to behave like a point light that will cast sharp shadows at a distance is just impossible?
I think I am missing some fundamental aspect of how light rays work here.
