DIY Forum gurus,
My roomate and I recently decided that the one thing our room lacks is a 96" projection TV. Thus, we went on the net to search for some guidence in building our own LCD projector. After a lot of poking around, we found 3 basic designs - the "Slap an LCD Panel on an overheard projector and call it a day" method, the "Use Lens and build a 5 foot monstrosity" method, and the "Projection Lens" projector. The compactness of the third DIY design seemed to us to be the simplest and easiest out there.
Our ideal model was zarks'...:
http://www.geocities.com/zark5150/projector.html
However, before following in the footsteps of zark, we wanted to ask you a few questions.
I searched to forums and got a lot of questions answered, but a few remain (which are probably just so obvious no one has mentioned them before 🙂
Anyway, here goes...
1) How good is the projection quality you get using a projection lens? Has anyone been able to compare it to the overhead projector method? Do you have problems with darker and lighter spots?
2) What resolution is standard for the LCD panel? Since most lens are only 5", we assumed it was like 320xSomething, but wanted to make sure there aren't 5" screens out there at 1024x768. Are there lens that are like 7-10" that might facilitate using a bigger LCD?
3) How do you determine the size of your final image? Is there a focus adjustment on the lens? Since we are in a fairly small dorm room, our distance from Wall to Projector is pretty set, we can only adjust it by a few feet - how can we make sure our final projected image will fill up all of our available space? (about 96" diagonally) We realize this might be a little big, but we'd still like to know how to adjust the image size...
4) Finally, what's the best way to focus light from your lamp(s)? A lens? A Fresnel Screen? (In this method do you need a Fresnel screen at all?)
Thank you SOO much for your help, if you could give us any advice at all, you will forever be remebered for helping two poor college students fufill the dream of playing Nintendo on a 96" screen, although you will also be guilty of helping them run up even more ridiculous credit card bills... 🙂
THANKS!
Rob & Ankit
My roomate and I recently decided that the one thing our room lacks is a 96" projection TV. Thus, we went on the net to search for some guidence in building our own LCD projector. After a lot of poking around, we found 3 basic designs - the "Slap an LCD Panel on an overheard projector and call it a day" method, the "Use Lens and build a 5 foot monstrosity" method, and the "Projection Lens" projector. The compactness of the third DIY design seemed to us to be the simplest and easiest out there.
Our ideal model was zarks'...:
http://www.geocities.com/zark5150/projector.html
However, before following in the footsteps of zark, we wanted to ask you a few questions.
I searched to forums and got a lot of questions answered, but a few remain (which are probably just so obvious no one has mentioned them before 🙂
Anyway, here goes...
1) How good is the projection quality you get using a projection lens? Has anyone been able to compare it to the overhead projector method? Do you have problems with darker and lighter spots?
2) What resolution is standard for the LCD panel? Since most lens are only 5", we assumed it was like 320xSomething, but wanted to make sure there aren't 5" screens out there at 1024x768. Are there lens that are like 7-10" that might facilitate using a bigger LCD?
3) How do you determine the size of your final image? Is there a focus adjustment on the lens? Since we are in a fairly small dorm room, our distance from Wall to Projector is pretty set, we can only adjust it by a few feet - how can we make sure our final projected image will fill up all of our available space? (about 96" diagonally) We realize this might be a little big, but we'd still like to know how to adjust the image size...
4) Finally, what's the best way to focus light from your lamp(s)? A lens? A Fresnel Screen? (In this method do you need a Fresnel screen at all?)
Thank you SOO much for your help, if you could give us any advice at all, you will forever be remebered for helping two poor college students fufill the dream of playing Nintendo on a 96" screen, although you will also be guilty of helping them run up even more ridiculous credit card bills... 🙂
THANKS!
Rob & Ankit
Follow Up Question...
One more question, if we are only projecting a TV image, will a higher resolution LCD help us at all, since the native resolution of NTSC is rather low (320x something, I think...)? If we step up our resolution to like 1024x768 but are still transmitting an NTSC image, it doesn't seem like it would help us at all.
I've heard of software than can step up NTSC resolution and then trasnmit it to an LCD in real time, but is this necessary, or can on simply blow up a standard NTSC resoltion image and have it still look good?
Thanks!
Rob and Ankit
One more question, if we are only projecting a TV image, will a higher resolution LCD help us at all, since the native resolution of NTSC is rather low (320x something, I think...)? If we step up our resolution to like 1024x768 but are still transmitting an NTSC image, it doesn't seem like it would help us at all.
I've heard of software than can step up NTSC resolution and then trasnmit it to an LCD in real time, but is this necessary, or can on simply blow up a standard NTSC resoltion image and have it still look good?
Thanks!
Rob and Ankit
see multiplexor's answer
Hi guys: I saw your post and understand your space concerns, it's been pointed out to me that I am by no means an expert in the "small panel" field (or any field for that matter....cept maybe auto-mechanics... an I dont think being a class A mech will help here LOL ) I will point you to multiplexor's post in the "check this plan" thread, it has relevance for your consideration.
If I can help I will.
zardoz
Hi guys: I saw your post and understand your space concerns, it's been pointed out to me that I am by no means an expert in the "small panel" field (or any field for that matter....cept maybe auto-mechanics... an I dont think being a class A mech will help here LOL ) I will point you to multiplexor's post in the "check this plan" thread, it has relevance for your consideration.
If I can help I will.
zardoz
Unfortunately, small high-res LCDs (6" and less) are extremely expensive. I know size can be a problem, but getting a high quality large panel is probably the way to go. However, that requires a fresnel, and I still don't know if there are quality prolems w/ the optics. I've heard that having the projector's lens far away from the panel can reduce the quality, but I haven't heard a definate explaination if that is really true (and if it is, why).
from looking at my fujinon lens,
it would appear that the size is set by pulling the projector back from the wall, and focusing is set with the distance between the LCD and the front of the lens... i think. havent had too much use with it yet (or any).
the delta lenses have focus adjustments on them i am pretty sure.
one thing i have noticed with the 4" LCD i have recieved in the mail.... HOLY SCREEN DOOR EFFECT BATMAN!
So that is something to watch out for, and is much less for 5" panels.
it would appear that the size is set by pulling the projector back from the wall, and focusing is set with the distance between the LCD and the front of the lens... i think. havent had too much use with it yet (or any).
the delta lenses have focus adjustments on them i am pretty sure.
one thing i have noticed with the 4" LCD i have recieved in the mail.... HOLY SCREEN DOOR EFFECT BATMAN!
So that is something to watch out for, and is much less for 5" panels.
Yeah, I think the screen door effect is from a low native resolution. Do you know what the resolution for your panels are?
the 4" one is from parts express, 383x234 i think... the 5" one is a psone monitor -- i would imagine it is about the same.
resolution looks about the same, but the screen door effect seems way worse to me on the 4" screen.
possibly due to some sort of minimum spacing between pixels... so the actual pixels get bigger in the 5" screen, but the size of the gap stays about the same? I dont really know here.
resolution looks about the same, but the screen door effect seems way worse to me on the 4" screen.
possibly due to some sort of minimum spacing between pixels... so the actual pixels get bigger in the 5" screen, but the size of the gap stays about the same? I dont really know here.
thus far...
most of the people who have gotten 5" LCD projectors to work properly have been fairly satisfied...but they werent expecting much out of them.
boils down to personal tastes i think.
I am making one for my room, will only probably be a 40"-50" screen.
For the living room I have better things planned.
Jay
most of the people who have gotten 5" LCD projectors to work properly have been fairly satisfied...but they werent expecting much out of them.
boils down to personal tastes i think.
I am making one for my room, will only probably be a 40"-50" screen.
For the living room I have better things planned.
Jay
Control image size
A person can control the size of the image projected by changing the size of image in front of the projection lens. This can be accomplished with a series of biconvex lenses, or a single lens if you have the space for a 3 foot long projector. play with a magnifying glass between your lcd and your projection lens and you will see what I mean. All you will have to do is keep the image from the magnifying glass at the correct focal length for the projection lens.
A person can control the size of the image projected by changing the size of image in front of the projection lens. This can be accomplished with a series of biconvex lenses, or a single lens if you have the space for a 3 foot long projector. play with a magnifying glass between your lcd and your projection lens and you will see what I mean. All you will have to do is keep the image from the magnifying glass at the correct focal length for the projection lens.
Shibby,
I'm considering making a setup as is in the following image (apologies that I've attached this image a dozen times in different threads, but it illustrates many things I'm dealing with currently).
Instead of using a -500mm concave lens, could I get a -300mm concave lens and have that give me an extra magnification for my short-dorm room problem?
Thanks for your optics help! I'm fine with the soldering, but the optics makes me think back to freshman physics and that gives me a headache. 🙂
Keep the imagination wheels turning!
--Clint
I'm considering making a setup as is in the following image (apologies that I've attached this image a dozen times in different threads, but it illustrates many things I'm dealing with currently).
Instead of using a -500mm concave lens, could I get a -300mm concave lens and have that give me an extra magnification for my short-dorm room problem?
Thanks for your optics help! I'm fine with the soldering, but the optics makes me think back to freshman physics and that gives me a headache. 🙂
Keep the imagination wheels turning!
--Clint
Attachments
I have questions about the figion lense. How close is your lcd to the lense? Does it make a large image in a small area? Here's an example if the lense is 2 feet away from the screen how big is the image?
I'm building a rear projection tv have already have frame of the tv and the screen build this is the last thing i need a low focal lenght lense.
On one of the post you said the 4in lcd is the same as the 5 but is not the 5 is 324x960.
I'm building a rear projection tv have already have frame of the tv and the screen build this is the last thing i need a low focal lenght lense.
On one of the post you said the 4in lcd is the same as the 5 but is not the 5 is 324x960.
HanClinto
I think you might be a little optimistic on the optics (pun not intended 😉 )
I think the odd's might be stacked in a pile against you as there are a TON of variables in this picture...soo many elements, all needing to be in "spot on alignment".
I put my 12 inch laptop panel on the OHP with no projection head mounted...LCD screen to ceiling distance about 7 ft then held the one really nice lens from a Delta tac3 CRT lens pack at about 20 inchs from the LCD. VIOLA an absolutely gorgeous image on my ceiling about 5 feet diagonal. I could stretch it to MUCH bigger if I tipped the OHP on it's side and got more throw.
Right now I'm using the junk OHP as is with it's shody optics and at 13 feet from the screen the image has to be shrunk to keep it small enough to fit the 14X9 feet I have available...and it still looks awesome. I keep it down to a 10ft diagonal so ya dont gotta crank yer neck around to see the whole scene 😉
zardoz
I think you might be a little optimistic on the optics (pun not intended 😉 )
I think the odd's might be stacked in a pile against you as there are a TON of variables in this picture...soo many elements, all needing to be in "spot on alignment".
I put my 12 inch laptop panel on the OHP with no projection head mounted...LCD screen to ceiling distance about 7 ft then held the one really nice lens from a Delta tac3 CRT lens pack at about 20 inchs from the LCD. VIOLA an absolutely gorgeous image on my ceiling about 5 feet diagonal. I could stretch it to MUCH bigger if I tipped the OHP on it's side and got more throw.
Right now I'm using the junk OHP as is with it's shody optics and at 13 feet from the screen the image has to be shrunk to keep it small enough to fit the 14X9 feet I have available...and it still looks awesome. I keep it down to a 10ft diagonal so ya dont gotta crank yer neck around to see the whole scene 😉
zardoz
Gyah. I'm getting so frustrated with optics and lenses and panels and fresnels and CRAP!
What you said only confirms what I've experimented with with my projection lens, laptop, and fresnel. I don't know jack diddly as much as I thought I did.
I've put a month of good research time into trying to figure out how to make my own compact projector. I think I'm going to relist my 5.6" LCD on e-bay and go the OHP route. I'm ready to forget the whole engineering DIY method and take the cop-out iwanttowatchbigmoviesinmydormroomcheaplyandquickly method.
A very frustrated engineering student,
--Clint
What you said only confirms what I've experimented with with my projection lens, laptop, and fresnel. I don't know jack diddly as much as I thought I did.
I've put a month of good research time into trying to figure out how to make my own compact projector. I think I'm going to relist my 5.6" LCD on e-bay and go the OHP route. I'm ready to forget the whole engineering DIY method and take the cop-out iwanttowatchbigmoviesinmydormroomcheaplyandquickly method.
A very frustrated engineering student,
--Clint
Don't get discouraged..
I think the basis of your plan looks really good, but I dont know too much on the optics end either.
I just know that the more elements in the equation, the more chances for error. The fuji lens is a really attractive piece of gear and if you can make it work I'm betting it would do an awesome job. I just think holding the intermediate elements might be a nightmare, and a lot of work (not that the effort isn't worth it, just might take longer to achieve primo resluts than you want to wait) Why not use the LCD you have? It should work on an OHP shouldn't it? I'm half tempted to use my junk OHP (as the light source) on it's side with the precise lens from the CRT pack (only one decent lens in the whole assembly). All in a custom box to hold the nice len's and the PC to run it all.
zardoz
I think the basis of your plan looks really good, but I dont know too much on the optics end either.
I just know that the more elements in the equation, the more chances for error. The fuji lens is a really attractive piece of gear and if you can make it work I'm betting it would do an awesome job. I just think holding the intermediate elements might be a nightmare, and a lot of work (not that the effort isn't worth it, just might take longer to achieve primo resluts than you want to wait) Why not use the LCD you have? It should work on an OHP shouldn't it? I'm half tempted to use my junk OHP (as the light source) on it's side with the precise lens from the CRT pack (only one decent lens in the whole assembly). All in a custom box to hold the nice len's and the PC to run it all.
zardoz
HanClinto said:
You are not really going to save space with the zark type design, I know it looks small, but his box is huge. The delta Iv alone is a very big, big lens. You may be interested in my approch. I put the 5" directly on the delta Iv and use the existing backlight to project (this makes for a very small projector and only needs to be a few feet from the wall for a 5-6 foot image). I got a good image, and all i need to do is modify the backlight so it is another 25,000 mcd brighter. Find the forum verbose mustafa project update.
good luck,
verbstafa
good luck,
verbstafa
Hey guys I see a few of you are getting concerned about your projection optics.
Its a piece of cake.
In most cases the light leaving your fresnel/LCD combination should be converging to a point X distance away. At that point maybe an inch or two before it is the right location for your projection lens and the lens does not have to be anything fancy.
One of the reasons guys use projection lenses is because it says "projection lens" on it. But that does not automatically mean it will be any good for your application. Some of these are really good lenses with zoom and excellent glass inside but if you don't know how to use one, it is a waste of time. A single lens will do just as well and is a lot less hassle.
As you know, if you have a flat piece of glass the light comes out one side at the same angle it went in at. There is no magnification with regular flat glass. You could take the glass away and the scene looks the same.
Lenses are flat glass that has been bent to a particular curvature and one side is often flat or curved more than the other side.
Lenses like that have gain or magnification.
You send a beam of light in at 10 degrees and it may come out the other side at 20 degrees, or 40 degrees. Or more.
This makes lenses very useful.
In most DIY projector applications the light coming from the fresnel/LCD combination is converging slowly to a point. It hits the projection lens and there is where you can controll what happens next.
If you use a lens with low magnification, the outgoing beam is not spread out very much so you use that type of lens if your projector is right at the back of your lounge and you need a long throw lens.
On the other hand, your projector might be in the middle of your room so you need a lens with more magnification to make the outgoing beam spread wider in a shorter distance.
A projection lens is the least of your worries. The real hard core DIY work is done in getting as much of the light as possible to go through your fresnel/LCD combo without cooking your LCD.
Check out Gunnawan. (Could be Gunawan) He posted a lot of very useful info about different types of lens and throw distances. He has a spreadsheet where you can dial in distances and the spreadsheet tells you what projection lens you need.
There is one important thing about projection lenses. The bigger the better. Big ones gather more light than small ones. The one in my 3M 1705 OHP is 3.5 inches in diameter and works really well
Surplus shed has lots of lenses. Surplus+shed on google will find it.
Or look in the links in the Wiki. There are lots of optics links.
Its a piece of cake.
In most cases the light leaving your fresnel/LCD combination should be converging to a point X distance away. At that point maybe an inch or two before it is the right location for your projection lens and the lens does not have to be anything fancy.
One of the reasons guys use projection lenses is because it says "projection lens" on it. But that does not automatically mean it will be any good for your application. Some of these are really good lenses with zoom and excellent glass inside but if you don't know how to use one, it is a waste of time. A single lens will do just as well and is a lot less hassle.
As you know, if you have a flat piece of glass the light comes out one side at the same angle it went in at. There is no magnification with regular flat glass. You could take the glass away and the scene looks the same.
Lenses are flat glass that has been bent to a particular curvature and one side is often flat or curved more than the other side.
Lenses like that have gain or magnification.
You send a beam of light in at 10 degrees and it may come out the other side at 20 degrees, or 40 degrees. Or more.
This makes lenses very useful.
In most DIY projector applications the light coming from the fresnel/LCD combination is converging slowly to a point. It hits the projection lens and there is where you can controll what happens next.
If you use a lens with low magnification, the outgoing beam is not spread out very much so you use that type of lens if your projector is right at the back of your lounge and you need a long throw lens.
On the other hand, your projector might be in the middle of your room so you need a lens with more magnification to make the outgoing beam spread wider in a shorter distance.
A projection lens is the least of your worries. The real hard core DIY work is done in getting as much of the light as possible to go through your fresnel/LCD combo without cooking your LCD.
Check out Gunnawan. (Could be Gunawan) He posted a lot of very useful info about different types of lens and throw distances. He has a spreadsheet where you can dial in distances and the spreadsheet tells you what projection lens you need.
There is one important thing about projection lenses. The bigger the better. Big ones gather more light than small ones. The one in my 3M 1705 OHP is 3.5 inches in diameter and works really well
Surplus shed has lots of lenses. Surplus+shed on google will find it.
Or look in the links in the Wiki. There are lots of optics links.
Delta Projx Lens
I just ripped open my Delta 20 projx lens and found a biconvex lens in between two convex lenses. If this is all that is involved in the projection, and it is half the cost to buy the biconvex lens alone, wouldn't this be better than buying the delta projection lens?
I dunno, maybe I'm just too bored....waiting for pay day to purchase my <a href="http://www.mp3playerstore.com/stuff_you_need/special/56tv.htm" target="_blank">5.6" TFT TV/Monitor</a> and <a href="http://www.homedepot.com/cmc_upload/HDUS/EN_US/asset/images/pii/9/9/9/2/A22999_2.JPG" target="_blank">65 watt Fluorex Flood Light</a>.
<b>Transient</b> I've been meaning to ask you this:
that isn't Ankit Fadia by any chance is it?
I just ripped open my Delta 20 projx lens and found a biconvex lens in between two convex lenses. If this is all that is involved in the projection, and it is half the cost to buy the biconvex lens alone, wouldn't this be better than buying the delta projection lens?
I dunno, maybe I'm just too bored....waiting for pay day to purchase my <a href="http://www.mp3playerstore.com/stuff_you_need/special/56tv.htm" target="_blank">5.6" TFT TV/Monitor</a> and <a href="http://www.homedepot.com/cmc_upload/HDUS/EN_US/asset/images/pii/9/9/9/2/A22999_2.JPG" target="_blank">65 watt Fluorex Flood Light</a>.
<b>Transient</b> I've been meaning to ask you this:
that isn't Ankit Fadia by any chance is it?
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