Well, I've been lurking and posting the forums for the better part of +5-6 years now, and due to an upcoming graduation party I'm hosting for a friend, I decided to kick off his freedom from high school with a outdoor rockband experience on a +120" screen.

I'm using:

Light: 400w MH PlusRite
Ballast: Venture 400w 4-tap V90D6413K
Reflector: Soup Ladle from Party Station
LCD: 17" Samsung
Fresnel: LL 220/650 fl Set
Triplet: LL Pro ?fl
Heat sheild: 1/4" Tempered Glass
Material: MDF

So my plan for this was to mearly get it working by this saturday at the cost of looks.

I want to do a bit more creative design, but i dont have the time.

I'm a bit scared to cut the fresnels, with my track record, I'll probably cut too much on one side, or cut the wrong side or something will go wrong. So for the time being I'm leaving them a full size.

So with that in mind I ordered most of the parts while still building the enclosure. -BAD IDEA for first timers

I ended up with a internal size of 16"x17" which is the size of the glass and the fresnels...leaves no room for air flow or to run cabling to the back.

I originally planed the box to be 3 feet long to give myself some extra room to play with, after last nights trial...It looks like i should have went with 4 feet. The triplet needs to be placed about 3 inches outside of my current enclosure. (I havent tweaked or shifted anything yet, but it seems lik my box shouldnt have to be THAT long)

While waiting for parts, i stripped my lcd down, pulled the AG, and framed it out.

I plan on using the temp controller as the interlock for the bulb if the lcd area gets too hot, any suggestions on probe placement? Top/bottom?

I may even use temp controllers as my on/off switch, they have run/stop setting that i believe allows for an alarm output. the control output would be my lamp, wheras my fans would be my alarms (set to always on).

This it just the prototype enclosure for now, when more time/money becomes availible, she'll get prettier...

The pic with the lights on, that's with a 100w incandescent on 12 feet way from the wall.

So the projector worked very well outside using my limbo pole/projection screen. The dissappoingting part of the party came at about 9:30 when it was dark enough to use the projector, everyone started to leave. So there was a total of 4 songs played with it all set up. Most people apparently didnt want to look like a fool on a big screen, which didnt en up being 120", it was only 90" the cheapest material i could find was a dollar store shower curtain.

So i did learn though that my fan-only cooling system was not providing enough cooling to keep the temp down. I was reading 87ŽºF and rising when i started to drill some holes in the side of my disposible box. that brought the temp down to 85 degrees, then i wired 2 more fans and placed those in the box, i had that beast down to 77 and falling in no time at all.

I noticed I was getting some additional light leaking through the lens, so I'll try to patch that up before time for the fourth of july party...then i can design a less monstrosity of a box.

I may have asked this before, but is it common with 17" screens to have a pj length of over 3 feet?

Pics from the party after everyone left. I'm in the last pic to try to so a size comparison

Nice work getting it all going.

Yes on the length. My straight shooter seemed like it went on forEVER ... Ever ... ever ...

Well, i wont have time to improve the look of it by the fourth, but I will be trying to construct a screen outside

I went over to home depot and bought 3 sheets of OSB, and had them cut it to 2'x8' sections so i could fit it in my car (Toyota Rav4).

I'm planning on painting them primer white and using 5 of the sections to make a 8'x10' screen, but i still havent figured out how to make them disconnectable so i can take it down easily afterwards. I have a fence in the backyard i can strap the lower halves of the sections to but I'm afraid the wind might make the upper halves flop a bit.

Had a fourth of July party, featuring the first Transformers. Turned out pretty good, the sound could have been better, but it was enjoyable.

Built a OSB 8 foot by 10 foot screen, 153" diagonal. It was comprised of 5, 2'x8' sheets. It was brad nailed to a piece of 2x4 on the corner of my fence to open up seating to the whole yard. I used painters tape on the seams and put two coats of paint over them, it seem to mask them quite well at night.

The only time i noticed the seams were when cars passed by, and it showed on the "two black bars" from watching a 16:9 on a 4:3 screen.

I was bit weary of using OSB at first, it being chipper-board and all, but by the time the movie got going, i didn't notice the subtle imperfections of the board at all.

My camera was set a bit differently this time than the last so the pictures came out a lot dimmer than the screen actually was. I was being pestered by an army of 9 year-olds to start the movie, so I just went with the default "auto" setting.

With flash


Without


Now that most of the get-togethers are over now i can start thinking about my box redesign

iSo I'm working on a redesign of the box now, and as much as i like the performance of unsplit setup, I'm pretty convinced to split it up. Finding a table tall enough to position the PJ perpendicular to the center of the screen is a bit of a problem.

Eventually I'm looking to construct a 12'x16' screen in the backyard, so unsplit I'd need a table/stand about 5' tall.

So I'm thinking, split the fresnals for the keystone benefit, and plop the PJ on the ground. But now the question is, what would be better, a center hinge keystone or a top hinge?

Since I'm projecting from the ground that would cause the top part of the fresnal to be the furthest from the LCD, will this cause any image distortion?

focalcalc tells me I need to be about 25 away from the center of the screen which is still within 15º even from the ground.

Catmandu, If your planning to go big I suggest you max out the efficiency of your light engine with the use of a precondensing lens such as this from Surplushed.com. I assume your using a 220mm fresnel and the focal should be adequate. So far, it’s the cheapest I could find on SShed aside from ebay at short notice and should be worth the effort. Just trying to help.

Will I need to adjust focal distances if i use a precondensor? or can I just build as planned and drop it in place later?


I do have a set of scrap Delta 101a's which is is a set of three quite large lenses. Any chance I could use one of those as a precon?

(i held one up to a CFL bulb and nearly blinded myself, it seemed to distribute the light across the lens very well before the room started spinning )

You should be closer so the ability to adjust should be in the plans.

Not knowing the focal of your lens I can't say but trial by error I suppose. But along with distribution you should get a brighter image especially if your going quite large as you've proposed.

Finally got back to working on the PJ tonight (gf worked night shift tonight...coincidence?).

I managed to get the pieces I've had cut for a month now screwed together...but, I'm not sure about the field Fresnel (the 650mm anyways).

I'm planning a center pivot, but in order to get a 15º swing both ways I'll need a distance from the LCD to be approximatly 60mm. I've seen 20mm has become somewhat of a standard, is there any reason I couldnt go that far without a loss in light(or clairty)? The light at that point should be collimated, no? so distance shouldnt be an issue i would think, short of it affecting the distance of the triplet, which I'm hoping will be adjustable.