MONSTER Projection/Screen project.......

Yes, I'm a newb here, but thanks to 12yrs in the Marines, my armour is TOUGH, so melt yur barrels returnin' fire for all I care....FLOL!

NOW, to the point.....I am hell-bent on making a front-projector without payin' the manufacturers' full-pop retail. I've got a 20' wide X 8' high X 60' deep room of granite block/wire reinforced concrete drywall with virtually no-light conditions if needed. I don't give a snot about big, nasty enclosures, and I'll put a diesel muffler/swamp cooler on the bulbs if that's what it takes!!!!! I am a builder at heart, so I'm not afraid of ANY construction/design work in steel, aluminum, wood, composites, concrete(yu get the picture)so long as there is some kind of useful instructions involved. My $1000 goal is this......fill a 15' X 8' section of that wall with a high quality DIY screen on a swing-down hardwood framing, then project a DVD movie image onto said screen that can be viewed at a distance of about 12', straight-on and have it look decent(and no, I'm not gonna go waltzin up to it at a foot away to see if it's got "screen-door" effect.) I am the "scrounger" incarnate, so you just tell me what parts I need, and I'll find 'em! And that goes for MAKING parts, too.......if some single component is too costly, but you know how to make that piece from scratch, tell me how to mill/cut/grind/lathe/weld/solder/assemble it, and I'll make it happen. So far by reading these posts, I got an idea I need at least one metal halide bulb in the 4200K range(what is the optimal "K", and what about clustering bulbs, ect?) Next, I DON'T understand the LCD "panel" sizing at all, so I'll need some input there(although I get it that 5" won't cut it; DOES IT EVER?????) Then, there's this little matter of the screen itself; I want to make that unit from scratch, and I do understand that it's construction needs to MATCH the projector's abilities, yes? Lastly, all I've got is a decent DVD player....no fancy wiring, and connector arrays, so if I need special connector types/quality, please be specific. SO, let's get to work, shall we?


And just so there's no misunderstanding, I'm VERY grateful to anyone willing to help me with this, and if you'd rather correspond through e-mail so as not to clog up these forums, it's [email protected]. THANK YOU!



And to those flame-throwers out there......you may fire when ready.:devilr:


BTW.......I like this guy's set-up.....any additions, different configs, ect?

400W MH light kit from lumenlab
the 80mm lens triplet and fresnels (330/220) from lumenlab
Proview 15.4inch lcd
Bunch of MDF board
60x60 Da-lite Video spectra screen
2 80mm fans (will be four when im done)
90mm diameter 305mm FL PCX condenser
2cm in diam. reflector
 

cbm5

Member
2005-03-14 12:47 am
Arkansas
You don't want to sit 12 feet away from a 17 foot diagonal screen. The effect is like putting your nose up to an intricate stained glass window...doesn't look like much when all you can see are the individual spots of color!

The 2000:1 contrast ratio ain't happening with a DIY projector. You would need to look into a DLP or CRT projector for that kind of performance. Since you have a lot of space, maybe you're a good candidate for picking up a used CRT and refurbishing it. Probably wouldn't struggle as much with a 17-foot screen, too.

Unless you know ALL the tricks our experienced DIYers have, and get really lucky, you won't do more than approach the contrast and brightness of consumer-level projectors. You get what you pay for, and the results we get are worth the few hundred dollars expense and cheaper bulbs. If a manufacturer produced an LCD projector with similar specs and similar price, most of us would buy it.

If you really want to go all-out and impress the buddies next Super Bowl, a commercial projector might be more your style. Always a bummer when the air vent gets clogged and people start to notice a dark spot in the middle of the screen....
 
OK then.....next stupid question......

What contrast ability can I expect, and how far back must my audience sit to fully appreciate the movie on a 17' diagonal screen? Mayhaps the distance will dictate a smaller screen, although they could sit back as far as 45' from the actual screen; any further, and they'll be underfoot in my wife's kitchen, and therefore dogfood.....FLOL! If the CRT is the only way to go for that kind of contrast, where is the best forum for that kind of discussion, since here seems to be only LCD? I do X-Ray and Catscan for a living, and know the importance of kVp and mAs on contrast and window leveling for computerized greyscaling, but the issue of color with these projectors always struck me as being the providence of the bulb's intensity and "K" range......is it not? THANKS, CBM5!
 

cbm5

Member
2005-03-14 12:47 am
Arkansas
For DIY projectors, the contrast you get is ALMOST the contrast that is specified for the monitor you used. I say almost, because you'll have some light bouncing around the inside of the projector even if you paint it black. Light outside the raycasted projection path will reduce your contrast a little. Typical used monitors are around 300:1 ro 350:1, simply due to progressing technology. A new monitor is going to be around 450:1. Probably not much more for 15" displays, because the 17" and 19" are the hot items now and the 15" models will always be the budget ones. Most DIYers find that anything above 250:1 pretty good for most uses.

You don't want to sit too far back (it's a bigscreen after all!), but obviously in your room you have the freedom to set it up and then move a chair until it looks right. You can figure it out by testing, there's no risk of being crowded against the opposite wall being confronted with Keanu Reeves' pores.

CRT projectors; do some searching in these forums, you'll get a good idea of what projectors were satisfactory for former DIY LCDers. Then go over to AVSforums and see what they have to say. There is always risk in getting a used projector, and you'll need to make sure that bulbs are available and that the tubes don't have burn-in marks. Nothing like the words "1998 Q3 Report - Foods Division" emblazoned across the Death Star.