As expected, the first results were not very good. However, there was definitely an image there, so I made a more precise version out of paneling, painted it flat black, and fine-tuned the lens mounting. The results were better, but still not near anything that you could actually watch a movie on.

   I had been able to get the focus quite sharp, but the brightness was never high enough to produce anything more than a dim, muddy image. In retrospect, some simple math could have told me that it was almost impossible to get a reasonably bright 50"+ image from a 13" televison. If you double the diagonal measurement, you quadruple the screen area. So my ~52" image could only ever be 1/16th as bright as the original. Add into this that you lose a good deal of the light from the TV before it reaches the fresnel, and it's obvious that this will never work very well.

   I was ready to give up on it, but did some more research to see what I might be missing. That was when I happened upon people who were building LCD projectors. The design is essentially the same as the projection television, but using an LCD means that you can control the brightness of the origin, unlike using a television.

   Some of these people were building quite complicated devices, with handmade light sources and lenses taken from old rear-projection televisions. However, it was quite easy to get in on the ground level: all you really needed was an overhead projector and an LCD Projection Panel.

   LCD Projection Panels are the fore-runners to today's LCD projectors. They are essentially LCD panels just like you would find in a laptop, but without a backlight. They were designed to be used on overhead projectors. Most were built in the mid-1990s, and at the time they ranged from $3,000 to $14,000 for the XGA models. True to form, the manufacturers didn't stick with this design and make them cheaper and better as the 90s progressed; instead, they replaced them with standalone LCD projectors, and now with DLP projectors.

   Most LCD panels that you find now on ebay are 640x480. A few are capable of 800x600, and one or two reach 1024x768. About half of the ones that you will find are substandard pre-VGA types that aren't truly capable of doing video projection. Minimum specs (in my opinion) should be 640x480 TFT, 100:1 contrast ratio, and 24-bit color (16.7 million colors). Some panels come with composite and S-Video inputs, but if a panel doesn't have these you will need to also purchase a scan doubler to convert the video image to VGA.

   The first panel I managed to snag was an InFocus PowerView 950. You see, after discerning that 24-bit color was minimum for video projection, I immediately went and got seduced by a panel with only 16-bit color, but 1024x768 resolution. As luck would have it, the panel was damaged in shipping and had to be sent back. After a few more weeks of lurking on ebay, I managed to score a Proxima Ovation 840 for $120. I overpaid a little for the panel because the seller threw in a 3M overhead for the cost of shipping. I also ordered a cheesebox scan doubler from avtoolbox.

   When the stuff arrived, I immediately set it up in an empty upstairs room. I dug an old VCR out of the basement and scrounged a scratch tape from the bookshelf downstairs. I hooked it all up and projected the image on one of the walls recently stripped of wallpaper.

   The results were iffy at best. Way, way better than the other projection TV, but still not completely watchable. I decided that the rough plaster wall was too dull to make a good screen, and the rest I blamed on the underpowered 2000 lumen OHP.

   I started hunting around for a material called Plas-Tex, which is a .060"-thick plastic waterproof wall covering that some people use as a projection screen because of its reasonable reflective gain. After a few days (including one memorable trip to Lowe's where the "expert" from the contractor's counter tried to convince me that Plas-Tex was, indeed, marine playwood, despite the fact that one is PLASTIC and the other is WOOD), I stumbled upon a butyl-impregnated canvas dropcloth that seemed to have a decent gain.

   Bought it, brought it home, and gave myself a lesson in canvas-stretching. Ended up with a quite nice 5'9"x4'4" wall screen. In the interim while I'd been hunting for a screen, I had brought our DVD player upstairs to the projector, but hadn't had a chance to hook it up yet. So the new screen debuted at the same time as the DVD player thru the panel.

   I was absolutely stunned at the enormous image that appeared on the screen. With a little fiddling, I had a razor-sharp ~86"-diagonal picture. A little experimentation revealed that either the old VCR or the scratch tape had been screwed up. I ran right out and rented 4 DVD movies.

   The different movies revealed another flaw in my setup. The weak OHP was incapable of throwing a good image of a 'dark' scene. 'Training Day' was pretty good, 'Gladiator' was marginal, and 'Panic Room' was unwatchable.

   I have spent some more time lurking on ebay looking for a more powerful OHP. I've been shooting for either an Elmo 305 or a Dukane 680, because these are 7000+ lumen 575W MH OHPs. Almost all of them go for more than $200, which is more than I have invested so far. So my current plan is to try to modify my current OHP to use a MH bulb, probably a cheap 400W setup. If it works out, I will outline it here.

   I bought a PAR56 parabolic reflector from partsexpress to tinker with. It's a 7"-diameter aluminum parabolic reflector. It comes with a G9.5 socket already installed. I toyed with the idea of first getting the 600W halogen bulb that goes with this setup, but seeing as it's halogen, and has a rated life of 75 hours, I decided not to.

   About the biggest problem with coming up with a custom lighting solution for this setup is the fact that the light source needs to be as close to parallel as possible to the LCD panel in order to optimize the light output. The temptation is to build a big sloppy box and hang a 1000W metal halide mogul bulb in it. Hell, with that much lumens you don't care if it all doesn't go directly out the apeture.

   Of course, being as obsessive as I am, that wouldn't be good enough. I decided that I needed to build what is essentially a narrow-beam spotlight of some kind to mount on the back of the OHP, replacing the current ENX bulb. The current bulb is about 2-1/2"-diameter. I can't find beam spread data on it, but it appears to be a pretty standard ellipsoidal reflector, and I'm assuming that the beam has to be roughly the diaganal measurement of the OHP (~14") plate by the time it reaches about 16 inches away (taking into account bouncing the beam off the internal mirror).

   Actually, as long as I can keep the beam angle narrow (to keep the light as parallel as possible), as long as I have a beam that is ~14" in diameter at the OHP plate, my custom light source should work.

   Now we start to run into problems with the low-cost MH bulbs: they're big. Like 9+" long. The size of the bulb pretty much dictates the size of the spotlight, and the larger bulbs are just too big. I researched some of the tubular single-ended bulbs; some of them looked promising. The course of action that I was following was to mount a G12-base tubular bulb in a parabolic or ellipsoidal reflector like so:

   This, I thought, was a very doable design. There was some work to get the bulb and reflector mountings just right, and then the prototype was going to have to be modifiable so that I could fine-tune the penetration of the bulb into the reflector... Then there was the fact that the largest single-ended G12-base bulb I could find was only 150W. Also, finding the sockets for sale by themselves was proving to be difficult.

   While I was searching for a good source for the sockets, I happened upon a PAR38 175W metal halide bulb. PAR38 is the standard design of most residential floodlights, with the reflector built right into the bulb.

Philips 31513-5 MH175/RSP PAR38 Clear, 16deg beam, Ave. 7500 hours, 65 CRI, 4100 CCT(K), 60,000 initial lumens

   Yikes! 60K lumens from a 175W MH bulb!?!

   No, of course it was not that easy. I haven't found anyplace that sells the lamp for a reasonable price (~60$). I also need to get the medium socket for it and the M57 ballast. All told (assuming I can get the lamp for $60) I should have the guts of a working 60K lumen semi-narrow spotlight for about $120. Woot!

   Applying some rusty trig, if my light source starts out as 4-1/2" diameter (diameter of the bulb), and has to be 14" in diameter at the OHP stage, then I get a distance of 16.5", which is roughly the distance I figured for the existing bulb.

   As soon as I can find the bulb for less than $80, I will be ready to go...