I get the impression that a larger LCD panel makes a larger projected picture. However, in the commercial LCD projectors the LCD has to be just two or three inches because the projectors themselves are so small. So can I use a two or three inch LCD and get a huge picture? Or is there some other magick going on inside the commercial LCD projectors?

Also... Would you all recommend using a widescreen LCD or a standard 4:3 ratio? I just ordered a Pro lens kit. What LCD would you all recommend? I'd like a huge, clear, bright picture.

There's two ways to increase or decrease screensize without moving the projector. One is by having a larger LCD or smaller LCD, and the second way is to have different lenses each having a different Focal Length or Multiplication Factor. That is how commerical projectors do it, they make that tiny LCD large by using lenses.

In most commercial PJ's (someone correct me if I am wrong) the LCD is smaller than an inch in size.

For our Projectors, using a larger LCD will give you a larger screensize for a given triplet. Using a shorter Focal Length triplet will give you a larger screensize for a given LCD.

Hope that clears things up a bit for you.

Crap! I just ordered the Pro lens thinking it would give a bigger picture, but it's focal length is bigger than the cheaper lens. So what's the advantage of the Pro lens? And can I still expect a big picture?

Oh yeah, it'll be as big as you want, the key is finding a good length that will give a sharp and bright picture . Check out the Focal Calculator in the Build and Calibration tools section.

So, just curious since I just ordered a Pro lens... what are the advantages of it over the $30 triplet standard lens??? Is it really worth it?

I've never had an 80mm Triplet but I hear that it is not really a true 80mm, more like 65mm. Someone please correct me if I am wrong, I am refering to the Clear Aperature which is the ONLY thing that matters in regards to that measurement.

Anyways, the Pro Lens has a larger Clear Aperature therefor it lets more light through the lenses giving you a brighter picture. That's one benefit.

The next benefit is that it has a longer Focal Length which does a few things. One, it places the Triplet further away from your LCD Panel, much further away. This gives it a much better chance at focusing clearly corner to corner on a 19" panel which is something the 80mm Triplet could never do. From what I have heard the 80mm can only just barely focus a 15" panel. So that is a big benefit.

Relating to Focal Length again, the 80mm Triplet has a Focal Length of somewhere around 330mm. This causes most people to place their Projector in FRONT of them while watching a movie. I'm not sure it that is what you want but most people don't. The Pro-Lens allows the Projector to be situated behind them while creating the same sized screen.

Anyways, that's the main benefits. If I was a rookie and not into spending thousands like I have, I would just blow the $200 once on the Pro-Lens. It should do a good job, I wouldn't know as I've gone a more expensive route.

~Lucky

You also get to be able to use a larger LCD panel with your projector, which results in higher resolutions. Most commercial projectors won't get you over 1024x768, which is what you can get with the standard lens setup (for half the money or less). With the pro lens, you can use up to a 19in panel in either widescreen (1440x900 most of them) or standard (1280x1024) aspect ratios. Higher resolution = better.

The widescreen panels (most for around 300 us) will also get you 720p HDTV (with a little letterboxing), which is also what some people are after.

The standard "80mm" triplet has an aperature of roughly 62mm. The pro triplet has an aperature of 100mm.

Bigger is not always better. There are other factors to consider. I find that with the standard triplet, and a 15" panel, this produces an image that is about as big as I would possibly want. In fact, since I want to be sitting where the projector is, it's a little too big for my liking. I can sit beside the projector, and that's what I was doing.

With the Pro lens, and a 17" panel, I was able to sit in front of the projector, so that I could sit on-center with the screen. The screen size was similar to what I'd had with the 15", but the projector was farther back is all. Of course there are limits to how far back the projector can be, because of the room size.

Now of course this depends on what size panel you are planning to use. If you got ahold of a 2" high res LCD (Like from a commercial projector) then a 500mm focal length lens is going to mean that you'll need to be projecting from a LONG ways away to get a big screen.

I will say that the extra step up in resolution from a 15" panel to a 17" panel makes a bigger difference than you would think. Going back to XGA was a big shock.

SupraGuy... thanks for the info. A couple other questions...
1) do I need a brighter light to project from further away?
2) can you recommend a good LCD to use with the Pro lens? Would a widescreen 17" be the best option?

Thanks.

i dont see as how a widescreen would be any benefit

a normal 17" monitor is perfect for 720p 1280x720 inside a 1280x1024 screen

perhaps if you went with something 1920x1080 you could deinterlace 1080i and display that (not worth the money in my opinion at that point you could buy a retail sanyo z3 and have much better contrast, size, noise, heat, and brightness)


good luck with your project

This is a DIY forum. But many people would likely be much happier with their results if they bought one of the newer Sanyo's or Panasonic home theater projectors.

I face the same dilemma again. I need a new PJ. Do I spend $1000-$2000 on state-of-the-art technology? Or do I spend nearly as much on building one that probably won't perform as well overall?

It's a lot easier to spend $100, $200 at a time, than it is to plunk down $2000 all at once.

But in the end, you spend about the same when you are all done...

And yet, I'll probably build another one. Because I think this is more than a hobby...it is like an addiction.

Hopefully there are no nasty side effects...

You mean like the side effects from standing in front of the microwave with it on and the door open.

Isn't running our projectors open and fooling with them about the same thing ?

Yes, if it has a metal-halide bulb inside.

I tried to warn you, didn't I?...

Is that just a joke? Or do metal-halide bulbs really emit dangerous levels of radiation? I'd like to know cuz my projector will probably be pretty close to where I sit to watch movies.

The metal-halide bulbs are like the sun - they emit a lot of infrared, visible light, and ultraviolet light (electromagnetic radiation and light are the same). However, the ozone layer blocks most of the UV-light before it reaches the surface of the earth. And yet still we can get sunburned easily depending on the level of our skin protection.

Here is the warning I posted when I sold my metal-halide bulb parts:

The reason I decided not to continue using them is because of safety concerns about the metal-halide UV-light emissions and also the mercury contained within. Before anyone operates this bulb they should fully understand these risks:

1. An unshielded metal-halide bulb presents a moderate risk of causing eye inflammation.

2. A broken MH bulb presents an extreme risk of serious eye damage or mercury poisoning, if handled improperly.

Because of these concerns, particularly for children, I've switched back to using a 400W halogen bulb and light engine from a 3M OHP with even better light capture than my MH setup.

And here is some advice I just gave to another member:

I think you are right to be concerned. I stopped using a metal-halide bulb because of the UV exposure danger, for myself and others. During building and testing I went to great lengths to protect myself. But I still found my eyes becoming irritated and inflamed at times. There's the open risk from exposure during experimentation - which is very high. Then there's the risk from the light leakage out the back of a projector during viewing. This amount of light seems very small. But it still is high frequency UV-radiation. And if you can see the light, then it is hitting your eyes. Our eyes are even more vulnerable in the low-lighting conditions.

You need to do some research on your own and understand these risks before diving into the world of high intensity discharge (HID) lamp usage.

All the best!

A couple questions:

1) Do UV filters, such as the ones LL sells, totally filter out all the UV?
2) What are the dangers of halogen bulbs, if any?
3) Do halogen bulbs put out enough light?
4) What type of bulbs are in commercial projectors?

I'll answer the one I know... heh

Nothing will ever totally filter out UV. However, just as Dajyn said, the earth's atmosphere blocks out UV, but not all off it. I think alot of ppl here forget that the glass most of us use will block a ton of UV. (Have you ever heard of anyone getting sunburnt inside?). Actually Dajyn explained it pretty well. Fiddling with the projector while the bulb is running isn't really a good idea (although we all do it anyway). Also the light leaks for our cooling systems and such probably shouldn't really be there either, but I don't really think they are that dangerous. It's worthwhile to note that prolonged exposure to these bulbs isn't really any different than staying out in the summer sun too long with no skin/eye protection. Same risks involved, just different exposure times. Standing in front of these bulbs for an hour is probably about the same as staying out in the summer sun all day (just a guess, don't hold me to that!).

I think what a lot of people are missing is that the type and manufacture of MH bulb will also affect the amount of UV emitted. If the bulb is rated open enclosure then it emitts a lot less UV than one that is not rated open enclosure. The open enclosure bulbs have UV protection in the outer envelope. The disclaimer on my old MH400U bulb package only warned against UV exposure if the outer envelope was broken. When I walk into Sam's club or other warehouse type of store (including the research bay at my work) I can see dozens of MH lamps on overhead without any type of barrier between them and us underneath. These types of bulbs are open enclosure types and emitt much less UV.

All of the larger lamps have good UV protection then if you use lexan it has UV protection then the back layer of the LCD has UV protection then most UV won’t bounce off the screen more UV protection

Then all you need is UV protected sunglasses

If you got the pro lens get the 17" LCD you will be happy.

Can anyone recommend a good 17" LCD that is easy to strip and doesn't have the FFC issue?

The picture I got out of my mockup box smoked my comercial projector...
My total bill so far is around $700. I can't imagine spending $2000 on this unless I broke 4+ LCD's or made the case out of titanium. Hmmmmmm titanium case....

Believe me, when you have the $2k in the bank, its far easier to plunk down the $2k than to DIY. The big reason for me to DIY is to not have to spend $350+ every 8 months on replacement bulbs. Thats like buying a new TV every 8 months... When replacement bulbs are $50 a pop, having a spare laying around is painless...

Here is what I have learned myself about halogens, through online research and usage in my projector:

2. The halogens have some risks like any other powerful light bulb. The small halogen bulbs commonly used in overhead projectors typically are made from quartz glass which offers very little UV protection. The good news is that they generate much less UV than HID lamps. The halogen light output spectrum is shifted to lower frequencies (mainly infrared and visible light). But like with any other extremely bright light bulb, you should still be cautious and take appropriate measures of protection.

3. Halogens can in fact generate adequate light for a projector. I am currently using a 400W EVD-type halogen bulb and a mirrored spherical reflector and aspheric condenser lens straight out of a 3M OHP. This produces a greater light output through my 15" LCD than did my 400W T15 metal-halide with LL eballast and Ikea reflector. Not only visually, but I've verified the significant improvement using a light meter. This is all the more amazing considering the 400W halogen is rated at less than half the lumens of the T15 MH lamp (16,000 versus 40,000). I am very satisfied with the light output now compared to my MH set up.

However halogens have several drawbacks compared to MH bulbs: Lower color temperatures, greater infrared output which we feel as heat, and much shorter bulb life - measured in the low hundreds of hours (or less) compared to thousands of hours for a MH bulb. But the bulbs themselves usually cost less than $10 apiece. Still, over time the halogens are more expensive to operate and less efficient.

4. To my knowledge, almost all commercial projectors use a metal-halide lamp today. However, it is fully encapsulated inside a sealed-beam type of reflector assembly. Presumably most of the dangerous UV is filtered out before it ever leaves the bulb assembly. So there is much less risk of exposure, baring serious internal damage that somehow manages to crack the bulb assembly - which isn't very likely.

I agree - $2000 is an extreme case of DIY projector "addiction", but not unheard of if someone is continually experimenting and building multiple versions of their projector(s). I think some people have even spent more than that so far...

$1000 range is much more common for most people, I would like to believe.

And I agree you can get good quality results that can smoke a lot of commercial projectors. But it all depends on which commercial model you are comparing to. You would be hard pressed to beat any of the last 2 or three generations of Sanyo or Panasonic home theater projectors.

But that's not to say anything isn't possible. Which commercial unit were you comparing your DIY projector results with?

Was it a home theater model or a business data projector?

Canon LV-5100U I have yet to compare it with my NEC.

For 2000$ you could buy a Z4 or 900u

I would argue my point, but the rational will accept fact and promote their hobby.

One which i also share.



that and im broke

I checked out the spec's on Canon's website. It is an older model business presentation data projector, and as such is optimized for high light output at the expense of poor video quality. The native resolution is only 800x600 (SVGA) and the contrast ratio is a poor 250:1. Brighness is rated at 700 ANSI lumens which is actually low for a data projector.

No wonder your DIY PJ smoked the Canon in image quality. The same will probably be true of the NEC.

But if you were to compare to one of the newer LCD home theater projectors, it would be a different story altogether. The latest models are rated at 1000+ lumens and 6000:1 contrast. Even last year's versions are superb performers, which I have seen myself.

Basically, it is unrealistic for us to think that we can build something on our kitchen table (for less money) that performs better than commercial models that companies have spent millions of dollars and years developing. However, I do believe that we can build something ourselves that works pretty decently and is quite satisfying and a lot of fun in the process.

My NEC is 1024x768,1300/1000 lumens. 2000/3000 hour bulb life.

I imagine the newer ones likely suffer from the same bulb cost the older ones do, possibly worse.

As for the contrast ratio, 6000:1 is marketing hype. I have heard that after 500:1, its diminishing returns. Telling a 500:1 projector from a 6000:1 projector might require a coin toss. Unless of cource you can have them both on at the same time, side by side with a test image.

Kitchen table? I am building mine in a fully stocked wood shop.

When your reason is to escape high maintence costs, some compromises are allowd. I am waiting until I am done to see what those are.

Have you built one by the way? Because if not, it may impact the credibility of what you are saying... Which would be like trying to sell lemons by talking down apples, which by the way, you have never seen, tasted, or held... I am not trying to pick a fight here, just making sure that you know what your talking about. I have been holding off on such wide sweeping statements until I finish, and can speak from experience with both.

Note to modorators: I think I/we hijacked this forum. You may move/delete my posts after a few days if you choose.

Yes, some experience with both DIY and commercial PJ's. Please see my posts above.

And I really did build mine on a kitchen counter/table.

i know you couldnt spend 300$ and get a better projecter then my 1280x1024 DIY PJ


i know for a fact you can spend 2000$ and net something better then you can build. resolution is fun and games for only so long. the plywood doesnt have the GAF (girl aproval factor).

My wife loves plywood

When my PJ is done I will have about $800 in it and it will be as bright as a commercial PJ and have vary high res It will be larger but a lot more fun!

Depends where you live. I know for sure that Magview 17's are ffc free. I'm watching one now. 12ms, no problems. Check the compatible monitors list, do a few days worth of reading of other plogs and posts, then get back to us.

so are the Benq 17" free too.. ehhh ffc's that is

I ordered the LL Pro lens the other day, and posters have been saying I should go with a 17" LCD. Well, I don't want my projector box to be bigger than it has to be so I'm wondering what the advantage is of a 17" LCD over a 15" LCD of the same resolution. And, won't a 15" LCD give me a larger screen size than the 17" at any given distance?

Or will the 17" really give me a better picture for some reason?

given the same distance from the screen, the 17" will give you a bigger picture... and you will find very few 1280x1024 native resolution 15" panels..generally, 17" panels also have higher contrast and possibly faster response times.... and the size difference (width and height wise) between a 15 and 17" is maybe an inch or two, no really all that noticeable...now using the pro, you will have a longer box(not sure how much, 4-6" maybe?)

So then what would be a good 17" LCD - without the FFC issue. Would one of these be good...

BenQ FP71G Black 17" 12ms LCD Monitor - Contrast Ratio: 500:1, 600:1(Max)
http://www.newegg.com/Product/Product.asp?...N82E16824014088

BenQ FP71G+ (Black) Black 17" 8ms LCD Monitor - Contrast Ratio: 500:1
http://www.newegg.com/Product/Product.asp?...N82E16824014100

15" = 1024 x768
17" =1280 x 1024 (need for 702p HDTV
The 15" and 17" don't have the same resolution. If you just want to watch regular old TV or DVDs then you don't need the 17" if you want HDTV or computer games then go for the 17". If you want small a 7" Lilliput (800x480) ot an 8" HAMI (800x600) might be a better bet.

Ok, thanks. That is the answer I've been looking for. I was not aware that 1024x768 was as high as the 15 inchers go. I'll be getting a 17" then. What's a good contrast ratio to look for?

*SIGH*

Nobody knows how to google...

Sample list of 1280x1024 15" LCD

Do a google search of your own if you want... You are now in the research phase of the project.

Good Luck!!!

So then is there any other reason to go with a 17" LCD?

I don't think there are 1280x1024 15" LCDs, or I'm yet to come across one anyway. The ones that claim to do it actually just scale the picture, so it's not the panel's true res.

When looking at specs, always look at the Native res, not the Max res for the panel.

sigh... no, we know how to google, but we also read the results of the google...first 3 I tried are not 1280x1024 native resolution, they are just standard xga 15" ..., now I'm sure you probably could find one somewhere if you googled hard enough, but the cost will probably be higher than a regular 17" .... you might try adding sxga to the google search but even then most will be xga ...

ps: the reason is the actual size of the pixels(understanding that really its 3 seperate subpixels for each "pixel", the most common (abd therfore cheapest) are .297mm and .264 ... multiply those by the native resolution and you'll see why there are very few (if any) 15" sxga lcds... now there are the wuxga 15.4" screens..but , not being as common and more expensive to make, they are commeasurately more expensive.... though if I had my pick, thats what I would go for.... unfortunately those are mostly used in laptops so you need a seperate controller for those

I opened myself up for this I have searched deeper, and was astounded that I couldn't find a > 1024x768 15" panel. My laptop is 1920x1280, so I just thought that 15" lcd's could easily hit 1280x1024. My gut tells me they are out there, but I cant seem to find them...

yeah , well, there is no reason 15" couldn't do sxga or wuxga, I mean just take the laptop screen and marry it to the right controller and some cheap plastic and voila!, but there is just no demand for them(on the desktop anyway, they'd probably start out costing twice any other 15") when you can get a 17"(or soon a 19") for the same price... laptops are a totally different story however... why? I have no idea why... except that laptops can only get so big...so there is only one way they can compete with other laptop makers(lcd wise).... in resolution.... ?

Like I said:

15" = 1024 x768
17" =1280 x 1024 (need for 702p HDTV
The 15" and 17" don't have the same resolution. If you just want to watch regular old TV or DVDs then you don't need the 17" if you want HDTV or computer games then go for the 17". If you want small a 7" Lilliput (800x480) ot an 8" HAMI (800x600) might be a better bet.
There are no 1280x1024 15" monitors. There are 1280x768 15.4" LCDs but the contrast isn't that good so people have stayed away for PJ usage.
If you want native HDTV either go with a 17" or get into minoten's 15.4" 1920x1200 LCD panel group buy ($715). 17" is the only cheap solution.

I'd recommend hanging on with your current setup for 6 months. I'd bet money that all PC and TV LCDs will be high contrast widescreen as soon as the pipelines of current junk are emptied.

I want 19" WSXGA for my next system. I could buy 1 now but they are still expensive.

I think 6 months is a bit soon, maybe christmas 2006? by then we might have the ellipsoidal small arc lamp/reflector brain has mentioned as his "ultimate" goal(my words).... have you ever seen a 19"wsxga? all the 19" I've seen are still1280x1024..of course I avoid even looking at anythin over 300$