I have all the parts needed to get going on my 7" Lilliput build. I got the standard lens kit and cut them down to about 5x7. I also picked up the varifocal lens.

I've got a Sylvania HQI-250DE 250W that I'm planning to run with an Ikea reflector.

I built the box and got some of the layout done, but am waiting on couple of the items to actually arrive. Hopefully I'll get some time to complete it by the end of this month.

One question, though - based on the calculator, it looks like I'm going to end up with a ~40" projected image from roughly 7 feet back. Am I correct in assuming that I would need to change the front fresnel in order to achieve a larger image at this distance?

Any help would be great. I'll add photos and diagrams when I get a chance.

Hey gubon13,
I'll keep an eye out for your plog. I'll be statting my 8" projector soon. I have an Ikea reflector and a piece of Plexi glass I got from ireplica's web site. not sure what to do with it though. I'll also be getting the 250w HQI bulb. Maybe I'll be able to learn some things from you. Reason I chose the 8" is the resolutions. The lilliput's res kind of scare me abit. I'm affraid the image wont be watchable.

Well, I got my bulb in today, but Atlanalightbulbs.com sent the wrong bulb. Or rather, they sent a different bulb. While I ordered the Sylvania HQI-DE 250/DX, I received an Osram HQI-TS 250 W/D UVS.

The HQI-DE 250/DX is rated at 5000K color temperature, and the HQI-TS 250 W/D is rated at 5100K. Other than that, I don't see much difference, and as far as I can tell, it's probably the same internals.

Also, I managed to thrash my Ikea reflector, so I went looking for an alternative that I could get locally in case my hand slipped again. At Bed Bath and Beyond, I found a Calphalon soup ladle ($10) that is 88mm in diameter. It is ridiculously shiny, but I will say that it's HEAVY DUTY. It took me hours to cut the slots for my bulb. After polishing it with Mothers, it is SHINY. Here's a link:Calphalon Soup Ladle

Hopefully I'll be able to fire up the light tonight and test it with and without the reflector.

I should post a photo, but I'm tired and lazy after being at work for so much this weekend. (And all I want to do is skip out and work on the PJ.)

I got it projecting a ~40" image that is pretty decent. Brightness seems awfully low. I'm starting to wonder if I should have just gone for the 400W instead... Argh.

Initial results look great at 50" diagonal. When I push it back to 100" diagonal, the brightness and colors just DIE. UGH!! More work to come, I suppose.

I'm starting to wonder if I should have gone with the 400W.

Click to enlarge:

Any pictures of the unit?

And are you using a condenser to improve brightness?

Joe

Here are some pictures of the unit. Yes, I am using a condenser, and something tells me that this is probably my biggest problem. While I see a significant increase in brightness using the condenser, I suspect that I need a larger unit with a different focal length.

This one was pulled from an old slide projector, and I don't know anything about it. It's roughly 2" across. I'm looking to find a 90mm one (or something in this range) with a focal length that will work better with the rear 220mm fresnel. Any ideas?

Unit from the top. It's 17.5" wide, 28" deep, and 5" high (interior). Please ignore the rough wiring and paint.


Front view


Ikea reflector, HQI, and condenser. I scrapped the Calphalon ladle because it wasn't giving me as much light output as the Ikea reflector.


Here you can see the bulb warming up. It's been on for roughly 45 seconds at this point. Based on where the light hits, I think I've got the right focal length, but I'm not sure.


Here's my temporary grounding strip from the power in to the eBallast. I realized when I got done that it looks more like LUMERLAB than LUMENLAB. Sigh. I was planning on cleaning it up anyhow...


Ultimately, I think that I'm going to have to chalk this unit up as a test. I am unhappy with the way the box came out, and I'll likely have to redo it all. I think I'm gonna go with a 1/2" MDF next time.

with a condenser you will want to place the collector fresnel at the point where the condenser fills the fl at a dia. of 90mm if that is the size of you condenser. Also you need to have a fan blowing on the condenser or it will get to hot and crack on you.

Joe

I figure the best you can do with that small a screen and a 250 watt bulb is about a 50 lumen PJ . With the condensor you might creep to the 70 range but it won't cut it with much more than your 40" or 50" image. You'll need some good condensor cooling if you do go with a big bulb and condensor.
I think trying to go with a shorter collimator lens could help a lot more than the bigger bulb.

Kirk

This is one of the condensers that I was looking it:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...AMEWA%3AIT&rd=1

Says 90mm with ~12" focal length. Just to be sure, you're saying that the collimator fresnel would need to be ~12" from the condenser, right?

Also, while it's hard to tell from the photos, the condenser is cooled via some air gaps around it that allow the air to flow through. Considering that it's only a 5"x7.75" tunnel, and I'm using a 120mm fan that pushes 80CFM, it keeps pretty cool. Also, since it used to sit 1/2" in front of a 150W halogen bulb, I'm guessing it's made of a very durable glass. I've had the PJ on for up to 2 hours at a time, and each time it's cool enough to touch in less than a minute.

Well, right now, it's laid out as such:

250W HQI ---> Condenser ---> 220mm Fresnel ---> LCD ---> 330mm Frensel ---> Varifocal Lens.

Distance from HQI to Collimator Fresnel is 220mm.
Distance from Collimator Fresnel to LCD is 15mm.
Distance from LCD to Condenser Fresnel is 22mm.
Distance from Condenser Fresnel to Varifocal Lens is 315mm.

What hurts with this setup most (aside from lighting problems) is that at 84" from the screen (which is where I'd ultimately like for it to go), I can only get a 46-50" image. I'm thinking of replacing the Condenser Fresnel with a 200-220mm fresnel to get an image of ~65". I just don't know if this will work with the varifocal lens. At ~65" it's bright enough that I don't want to shoot anyone...just yet... I was really shooting for something in the 80-90" range.

I don't mind the idea of increasing the cooling as I will likely rebuild the enclosure as noted earlier. This would mean that I could redesign the whole thing.

I'm confused as to why I'm getting so little brightness considering the results I've seen from others here and at ALLINBOX. My guess was that the condenser was a major suspect in my setup.

How exactly would a shorter collimator fresnel help? (Forgive my ignorance.)

I was looking around, and I think that THIS is the exact same condenser that I'm using. I'm trying hard to remember what the dimensions were exactly (as I'm at work right now) but this sure looks to be about right. Assuming that it's the same condenser, it shows a focal length of 84mm. I will try to push the HQI, reflector and condenser to about 90~100mm away from the collimator and see if that makes a difference. You know, other than melting my collimator...

The light from the bulb drops off as the distance to the LCD increases. The closer the bulb is to the LCD - the more light you end up collecting at the first fresnel. In order to get it closer you need a shorter F.length collimator. This is a problem on 15" LCD's because as the bulb gets closer to the middle of the LCD the ratio to the corners gets larger. The result is darker looking edges. On 7" screen this is not a problem so moving the bulb closer does not effect the edge ratio as much.

A small glass condensor lens like your using helps this situation by getting very close to the bulb and getting most of the light headed in the useable direction. The main problem there being they tend to get very hot and need direct blast cooling to keep them from busting.

Not using a condensor and Just moving the bulb to half the distance will increase its brightness by 4 times. This should make up for the 4 times less screen area that your working with. End result should be that you'll be halfway back to the light output of a large projector (still only 250w not 400w remember) and should be able to throw a lot more brightness at the larger distance.

Kirk

Sorry if this is a little off topic but I was wondering which model of the lilliput 7 inch you used there seems to be so many versions available compared to.

I'm not sure. It's VGA, but otherwise, I'm not sure what model it is. I've long since lost the case, so let me know if there is somewhere else you would like me to look to identify it.

So I should try with a new set of fresnels? I've had a very hard time trying to source fresnels with <200mm focal lengths.

If anyone has any idea where I can find fresnels with 150~180mm focal lengths (preferrably 165mm), please let me know.

As of now, the project is on hold as things have picked up at work, and I have to clean my place because my girlfriend is returning from law school soon...

I found some time yesterday to test with the HQI at about 2/5 closer to the rear fresnel (with the condenser). WOW - HUGE DIFFERENCE. At 57" diagonal, the image was very bright and the colors were very nice. I am dead set on finding a new rear fresnel and matching condenser as this appears to be the solution to my problem. I can only speculate how much light loss I'm getting by having a 220mm fresnel with a light source ~130mm away with a small condenser.

Hooray for more parts I didn't expect to buy!

This project is officially on hold as my GF is still in town, and I had a major cash flow issue. My truck decided it no longer wanted anything to do with me, and so I ended up having to purchase a new car. Needless to say, I'm hurting for cash right now, and the project must wait. Sigh...