experiment!
I think you are in an ideal position: You already have all of those lenses, so you can try them all once you have your lamp/heat filter/LCD/fan assembled.
The only suggestion I have is to make sure that all of the light is actually making it to each of the lenses. A large diameter lens that has a very short focal length will be close enough to the LCD to capture all the light coming through from your parabolic reflector lamp. But some of the smaller diameter or longer fl lenses may not intersect the entire cone of light diverging from the LCD. For those lenses, it might help to add a weak condensor lens just under the LCD to get the light converging toward the projector lens.
If you can see screendoor, then you have two things present: Enough magnification to make it visible, and a very sharp focus. Every LCD made has a screendoor-like structure, because there are conductive metal traces between each dot of liquid crystal material. You can just ignore it, since you will probably be sitting far enough away not to see it. Or go with a smaller image. Some people are so bothered by it that they purposefully defocus a bit to get rid of it. That seems kind of silly to me.
I think you are in an ideal position: You already have all of those lenses, so you can try them all once you have your lamp/heat filter/LCD/fan assembled.
The only suggestion I have is to make sure that all of the light is actually making it to each of the lenses. A large diameter lens that has a very short focal length will be close enough to the LCD to capture all the light coming through from your parabolic reflector lamp. But some of the smaller diameter or longer fl lenses may not intersect the entire cone of light diverging from the LCD. For those lenses, it might help to add a weak condensor lens just under the LCD to get the light converging toward the projector lens.
If you can see screendoor, then you have two things present: Enough magnification to make it visible, and a very sharp focus. Every LCD made has a screendoor-like structure, because there are conductive metal traces between each dot of liquid crystal material. You can just ignore it, since you will probably be sitting far enough away not to see it. Or go with a smaller image. Some people are so bothered by it that they purposefully defocus a bit to get rid of it. That seems kind of silly to me.
NOw that I remember... the slide projector where I got the anastigmat lens for had 2 lenses... I think one was a small consendor right after the lamp, and then a double convex lens... kinda like
reflector -- bulb -- condensor -- double convex -- slide copartment -- lens.
I bet I could use them in this design if I don't get all the light... I'd just had to try to get it off the projector (it's one of those old ones made or very sturdy steel and stuff...)
reflector -- bulb -- condensor -- double convex -- slide copartment -- lens.
I bet I could use them in this design if I don't get all the light... I'd just had to try to get it off the projector (it's one of those old ones made or very sturdy steel and stuff...)
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@$#%@#%%@ !!!1
I can't get it to work right !!!! @#$@$#%@#$ !!!!
Ok so I got some spare time, so I decided to get everything setup for experiments... made the lcd frame, got the lamp holder, the mirror, etc.... but I can't get it to work right !! First, it's pretty hard to get the mirror at a right angle... then I try testing it with different lenses and the give me about a bright circle, and the corners are either cutoff or not lit at all !!! And I've still got light leakage... I then mounted one of those magnification things for gameboy, and there was more light, but still had those corners cutoff.
What I don't get is why there are dark spot, if all the light should be going through the tiny 2.6'' screen... would it be the lenses' fault? (I guess all this is my fault after all...
)
Guy, or even ace, could you help me out !?!? Man, I was SOO frustrated I thought about quitting... then I realized everybody has to start from something, and there is not better learning than experiencing things hands-on sometimes... but it's always better with a little help from my friends...
I need some help !!! Thanks in advance fellers !!!
I can't get it to work right !!!! @#$@$#%@#$ !!!!
Ok so I got some spare time, so I decided to get everything setup for experiments... made the lcd frame, got the lamp holder, the mirror, etc.... but I can't get it to work right !! First, it's pretty hard to get the mirror at a right angle... then I try testing it with different lenses and the give me about a bright circle, and the corners are either cutoff or not lit at all !!! And I've still got light leakage... I then mounted one of those magnification things for gameboy, and there was more light, but still had those corners cutoff.
What I don't get is why there are dark spot, if all the light should be going through the tiny 2.6'' screen... would it be the lenses' fault? (I guess all this is my fault after all...
)Guy, or even ace, could you help me out !?!? Man, I was SOO frustrated I thought about quitting... then I realized everybody has to start from something, and there is not better learning than experiencing things hands-on sometimes... but it's always better with a little help from my friends...
I need some help !!! Thanks in advance fellers !!!
corners cut off
It could be that your LCD is just too big for the lenses, if they are all designed for 35 mm slides.
Start by troubleshooting the light path:
1. Put a piece of white paper at the surface of the LCD that faces the light. Is it evenly lit, from corner to corner? If not, then adjust your light until it is.
2. Put a piece of white paper on the back surface of your projection lens. Is all of the light coming through the LCD falling on the lens?
3. If those are both okay, then try using a big magnifying glass as your projection lens. Measure the focal length using the sun. Put the lens at a bit more than the focal length from the LCD, then move it back and forth until you get a focussed image. (Screen must be at least a few feet away.) Does that give you an image with the corners lit?
It could be that your LCD is just too big for the lenses, if they are all designed for 35 mm slides.
Start by troubleshooting the light path:
1. Put a piece of white paper at the surface of the LCD that faces the light. Is it evenly lit, from corner to corner? If not, then adjust your light until it is.
2. Put a piece of white paper on the back surface of your projection lens. Is all of the light coming through the LCD falling on the lens?
3. If those are both okay, then try using a big magnifying glass as your projection lens. Measure the focal length using the sun. Put the lens at a bit more than the focal length from the LCD, then move it back and forth until you get a focussed image. (Screen must be at least a few feet away.) Does that give you an image with the corners lit?
Puzzled
Ok so I did my tests again. 🙄
Bulb facing the cold mirror, moved it until I found a circle that covers the lcd with a piece of paper... it seemed to cover all of it.
The I checked with the piece of paper after the lcd... I could see the square and the unfocused image...
Then I tried with the lenses... but still giving me dark corners... tried adjusting color, brightness and contrast but still the same...
Then I changed the light path, got my hot mirror and set it in front of my bulb (BTW, I set the cold mirror behing a plastic support while I was doing my test - bad idea, when I removed the plastic it've been starting to soften up !!! -
) ...
Then I went to find my page magnifier... I could not find it - but I did find a frsnel from a non working OHP, so I popped it at about 7'' from the lcd.... and VOILA !!! a super bright and almost clear picture, all corners lit, but of course not as big as with the lenses.... but I couldn't believe my eyes !! I had the screen at about 50'' or 60'' away from the fresnel and I got a 30'' image, almost clear (considering it's a fresnel). the I turned all the lights on in the room and living room, and the image was very watchable...
Then I thought about projecting further... so I moved the screen at about 170'' away from the fresnel... and got a bright 60'' image, turned the lights on, still very watchable...
At first I was trying with cartoon finding nemo, but then I moved on to The terminal, but still the image was great (you could not see all the details in the barckground, but you could see almost everything, specially close-ups).
Some additional information: I'm using a lenticular screen (I guess that helps make it watchable with lights on), and also, with the bulb and hot mirror, if I put my hand in front of it, I could still feel heat, but the lcd never got warm... this was without a fan (I will surely use one).The hot mirror was virtually right next to the buld (maybe couple mm in between).
OK..... now to draw some sort of conclusion... where do I go from here? If I stick to this design the projector might be awful long, but at least I know it works... I'm afraid light output will be affected if I used a FS mirror (comments on this)... and should I keep the fresnel as my objective lens?? The fresnel if designed for an OHP so it's awful big, and I would have to cut it down to fit... how do I do that? And also, I think I can get a hold of a thicker fresnel that would produce better quality... am I onto something?
So many questions... and to think that I was ready to quit and give up.... NO WAY JOSE ! 😀
Thanks in advance for all your help !!! Keep the ball rollin' !! 🙂
Ok so I did my tests again. 🙄
Bulb facing the cold mirror, moved it until I found a circle that covers the lcd with a piece of paper... it seemed to cover all of it.
The I checked with the piece of paper after the lcd... I could see the square and the unfocused image...
Then I tried with the lenses... but still giving me dark corners... tried adjusting color, brightness and contrast but still the same...
Then I changed the light path, got my hot mirror and set it in front of my bulb (BTW, I set the cold mirror behing a plastic support while I was doing my test - bad idea, when I removed the plastic it've been starting to soften up !!! -
) ...Then I went to find my page magnifier... I could not find it - but I did find a frsnel from a non working OHP, so I popped it at about 7'' from the lcd.... and VOILA !!! a super bright and almost clear picture, all corners lit, but of course not as big as with the lenses.... but I couldn't believe my eyes !! I had the screen at about 50'' or 60'' away from the fresnel and I got a 30'' image, almost clear (considering it's a fresnel). the I turned all the lights on in the room and living room, and the image was very watchable...
Then I thought about projecting further... so I moved the screen at about 170'' away from the fresnel... and got a bright 60'' image, turned the lights on, still very watchable...
At first I was trying with cartoon finding nemo, but then I moved on to The terminal, but still the image was great (you could not see all the details in the barckground, but you could see almost everything, specially close-ups).
Some additional information: I'm using a lenticular screen (I guess that helps make it watchable with lights on), and also, with the bulb and hot mirror, if I put my hand in front of it, I could still feel heat, but the lcd never got warm... this was without a fan (I will surely use one).The hot mirror was virtually right next to the buld (maybe couple mm in between).
OK..... now to draw some sort of conclusion... where do I go from here? If I stick to this design the projector might be awful long, but at least I know it works... I'm afraid light output will be affected if I used a FS mirror (comments on this)... and should I keep the fresnel as my objective lens?? The fresnel if designed for an OHP so it's awful big, and I would have to cut it down to fit... how do I do that? And also, I think I can get a hold of a thicker fresnel that would produce better quality... am I onto something?
So many questions... and to think that I was ready to quit and give up.... NO WAY JOSE ! 😀
Thanks in advance for all your help !!! Keep the ball rollin' !! 🙂
where to go from here
If you are happy with the image size and throw distance, then I think the next step would be to replace the projection fresnel lens with a PCX (good) or positive meniscus (better) lens of the same focal length. You only have an image field angle of 20.3%, which either lens type should do well. If you don't know the focal length of the fresnel, take it out around noon and measure the distance to the smallest image you can make of the sun. Don't buy a shorter focal length PCX or positive meniscus: If you want a larger field angle, you will need to go to a duplet or triplet lens.
A glass lens should be sharper and not have as much loss as a fresnel, but you might want to experiment with a stop aperature on the fresnel before you decide what size lens to buy. Cut a 100 mm diameter circle in a piece of cardboard and use that to cover the fresnel. If most of the light is hitting the hole, then the image will not get much dimmer. If it does get a lot dimmer, then you will need to add some focussing using a condensor system to get the light pointed toward the center of the lens.
If you are happy with the image size and throw distance, then I think the next step would be to replace the projection fresnel lens with a PCX (good) or positive meniscus (better) lens of the same focal length. You only have an image field angle of 20.3%, which either lens type should do well. If you don't know the focal length of the fresnel, take it out around noon and measure the distance to the smallest image you can make of the sun. Don't buy a shorter focal length PCX or positive meniscus: If you want a larger field angle, you will need to go to a duplet or triplet lens.
A glass lens should be sharper and not have as much loss as a fresnel, but you might want to experiment with a stop aperature on the fresnel before you decide what size lens to buy. Cut a 100 mm diameter circle in a piece of cardboard and use that to cover the fresnel. If most of the light is hitting the hole, then the image will not get much dimmer. If it does get a lot dimmer, then you will need to add some focussing using a condensor system to get the light pointed toward the center of the lens.
Ok, got some pictures to show the setup. I took them last night, got the setup running for about an hour or longer, and had no heat problems (I think/hope). they are not the best but I'll try to explain them.
This first one shows the setup (is not enclosed, and gives you a vague idea of what I'm working with so far.
This first one shows the setup (is not enclosed, and gives you a vague idea of what I'm working with so far.
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One more, with the LIGHTS ON. The projection is actually brighter than it seems (thanks to the lenticular screen). The cloth on top of the screen is blackout cloth that I used for some testing... the colors are a little little better with it, but cannot see anything with lights on.
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The bottom line....
It is great to have a bright and decent picture, but I am not happy with the image size and throw distance... unles there was no other way for me to go. SOOO, I would like to find a lens that does the job the fresnel is doing, but with a bigger image at about the same throw or less... so should I look for a lens with bigger barrel to cover the whole lcd? BTW, I found my page magnifier, put it on front of lcd... had to go WAY far from the lcd, and projected a smal, blurry image... so much for the 100'' scam!
For the PCX lens, I have one from the gutted OHP I used the frsnel from... I'll try some testing with it tonight.
Christmas break is coming and that means more time to experiment. BTW, I was able to find a 250w MH setup for $50... I will try to use that to rtrofit an OHP... anyway, I'll keep working !!
One last picture. Movie: The terminal - widescreen. Lights on. Viewable Size: 35'' Experience so far: Pricele$$
It is great to have a bright and decent picture, but I am not happy with the image size and throw distance... unles there was no other way for me to go. SOOO, I would like to find a lens that does the job the fresnel is doing, but with a bigger image at about the same throw or less... so should I look for a lens with bigger barrel to cover the whole lcd? BTW, I found my page magnifier, put it on front of lcd... had to go WAY far from the lcd, and projected a smal, blurry image... so much for the 100'' scam!
For the PCX lens, I have one from the gutted OHP I used the frsnel from... I'll try some testing with it tonight.
Christmas break is coming and that means more time to experiment. BTW, I was able to find a 250w MH setup for $50... I will try to use that to rtrofit an OHP... anyway, I'll keep working !!
One last picture. Movie: The terminal - widescreen. Lights on. Viewable Size: 35'' Experience so far: Pricele$$
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choices
From the images of your setup, it looks like the light is spreading out from the LCD. The big fresnel collects a lot of that light. If you just stick a smaller glass lens in there instead, it will only collect a small part of that light. I would say you have two options:
1. Get a CRT projection lens that is bigger than your LCD, and has to be put very close to the LCD. That will collect most of the light.
2. Put one or two fresnels an inch before the LCD to converge the light to a triplet. Some of the DIY sites sell triplets for as low as $29.
From the images of your setup, it looks like the light is spreading out from the LCD. The big fresnel collects a lot of that light. If you just stick a smaller glass lens in there instead, it will only collect a small part of that light. I would say you have two options:
1. Get a CRT projection lens that is bigger than your LCD, and has to be put very close to the LCD. That will collect most of the light.
2. Put one or two fresnels an inch before the LCD to converge the light to a triplet. Some of the DIY sites sell triplets for as low as $29.
Thanks Guy for following this thread and keeping an eye on me. I really appreciate it.
Ok, did more testing. I finally got my 70'' projection... but the projector was at about 200'' from the screen... that's about 16 feet. But the picture was still bright, even with lights on.
Is the lenses on OHP's PCX? If so I think it is not going to work.. I tried mine and it had to be far away to show the picture, and it was small... of course OHP use mirrors and all.... what's your comment on it?
About the light leaking out, my thoughts are that since it's not enclosed I might be losing a lot of light, but once I enclose the unit the problem will be solved somewhat. And of course I would have to cut the fresnel to fit.
About other lenses, let me throw you some links to see which one would work better in your opinion...
http://www.surplusshed.com/pages/item/l3077.html
http://www.surplusshed.com/pages/item/l2006d.html
http://www.surplusshed.com/pages/item/l3132.html
http://www.surplusshed.com/pages/item/l3290.html
http://www.sciplus.com/category.cfm?subsection=21
http://www.goldmine-elec-products.com/products.asp?dept=1096
I've got a fujinon projection tv lens (145mm diameter) which I've comment on before, but the thing with this is that it has to be right next to the lcd, and not sure if I can get the controller board out of the way (more than 90 degrees)...
Will keep experimenting, that's for sure. I'll get a hold of the other fresnel today, and will try to run test during daytime. Hope to hear from you soon. Thanks !!
Ok, did more testing. I finally got my 70'' projection... but the projector was at about 200'' from the screen... that's about 16 feet. But the picture was still bright, even with lights on.
Is the lenses on OHP's PCX? If so I think it is not going to work.. I tried mine and it had to be far away to show the picture, and it was small... of course OHP use mirrors and all.... what's your comment on it?
About the light leaking out, my thoughts are that since it's not enclosed I might be losing a lot of light, but once I enclose the unit the problem will be solved somewhat. And of course I would have to cut the fresnel to fit.
About other lenses, let me throw you some links to see which one would work better in your opinion...
http://www.surplusshed.com/pages/item/l3077.html
http://www.surplusshed.com/pages/item/l2006d.html
http://www.surplusshed.com/pages/item/l3132.html
http://www.surplusshed.com/pages/item/l3290.html
http://www.sciplus.com/category.cfm?subsection=21
http://www.goldmine-elec-products.com/products.asp?dept=1096
I've got a fujinon projection tv lens (145mm diameter) which I've comment on before, but the thing with this is that it has to be right next to the lcd, and not sure if I can get the controller board out of the way (more than 90 degrees)...
Will keep experimenting, that's for sure. I'll get a hold of the other fresnel today, and will try to run test during daytime. Hope to hear from you soon. Thanks !!
what next
OHPs use either a triplet, or a symmetrical duplet. Either one should work with your LCD, but if you take apart a symmetric duplet that is (lens mirror lens), then you need to put both lenses in a tube with the same spacing as the original setup. If there was a stop aperature, or the mirror was smaller than the lens diameters, then you need to add a stop aperature midway between the lenses. Otherwise you get a bright middle and dim edges. The lenses in a symmetrical duplet are either PCX or positive meniscus. Don't try to use just one lens, since that would have about half the focal length of the pair together.
I think your choices are clear: Either go with the Fujinon CRT lens by moving your controller board a bit more, or add some fresnels behind the LCD as a condensor system to get all the light pointing into something like your Kowa copy lens. Using a fresnel as the projection lens will never work well. You alread got both of these lenses to work, now you just need to adjust things to get one of them to work well.
OHPs use either a triplet, or a symmetrical duplet. Either one should work with your LCD, but if you take apart a symmetric duplet that is (lens mirror lens), then you need to put both lenses in a tube with the same spacing as the original setup. If there was a stop aperature, or the mirror was smaller than the lens diameters, then you need to add a stop aperature midway between the lenses. Otherwise you get a bright middle and dim edges. The lenses in a symmetrical duplet are either PCX or positive meniscus. Don't try to use just one lens, since that would have about half the focal length of the pair together.
I think your choices are clear: Either go with the Fujinon CRT lens by moving your controller board a bit more, or add some fresnels behind the LCD as a condensor system to get all the light pointing into something like your Kowa copy lens. Using a fresnel as the projection lens will never work well. You alread got both of these lenses to work, now you just need to adjust things to get one of them to work well.
Hi,
The OH lens is a singlet.... I tried with the mirror but did not get good results. 🙁
I gutted out the lenses from the slide projector - one is a double convex, about 2.5'' diameter, the other is a small condenser that was placed right after the bulb to collect the light. Anyway, I put the convex in front of the lcd and got a big image but it was hard to focus... put is behind the LCD and the light output incresed a bit- but not too much. Then I tried the condenser, about the same results.
I got a hold of the other fresnel, from an Apollo 2210, it is thick and both sides of it are soft, no ridges... so I'm thinking there are 2 fresnels glued together or something... this increased brightness a little, but not a whole lot compared to the other fresnel (from a 3M 9050).
Do you know if there are any CRT lenses that are smaller than the average ones? The one I have is huge compared to the tiny screen I have... or I could try to find a lens that is big enough to cover the entire LCD... I saw a lens on Ebay from a kodak slide projector that cover 7'' or so... I wonder if that would work better than the ones I have...
another question I have: I went to Lowes and they had this 50w 12v dichroic bulb with a 15 degree beam and UV stop... is it any good for what I'm trying to set up?
Thanks for your help.
The OH lens is a singlet.... I tried with the mirror but did not get good results. 🙁
I gutted out the lenses from the slide projector - one is a double convex, about 2.5'' diameter, the other is a small condenser that was placed right after the bulb to collect the light. Anyway, I put the convex in front of the lcd and got a big image but it was hard to focus... put is behind the LCD and the light output incresed a bit- but not too much. Then I tried the condenser, about the same results.
I got a hold of the other fresnel, from an Apollo 2210, it is thick and both sides of it are soft, no ridges... so I'm thinking there are 2 fresnels glued together or something... this increased brightness a little, but not a whole lot compared to the other fresnel (from a 3M 9050).
Do you know if there are any CRT lenses that are smaller than the average ones? The one I have is huge compared to the tiny screen I have... or I could try to find a lens that is big enough to cover the entire LCD... I saw a lens on Ebay from a kodak slide projector that cover 7'' or so... I wonder if that would work better than the ones I have...
another question I have: I went to Lowes and they had this 50w 12v dichroic bulb with a 15 degree beam and UV stop... is it any good for what I'm trying to set up?
Thanks for your help.
50 Watts?
>CRT lenses that are smaller
I guess you could ask the electronics goldmine website the diameter of their TV projection lens. If that is smaller, it might work for you. I think they come in a lot of different sizes.
>50 Watt dichroic bulb
Dichroic reflectors are great, and a 15 degree beam would let you use a single lens to converge the light to the projection lens. Or maybe with a large enough lens, you wouldn't need to converge it at all. But you need a certain number of lumens per square foot of screen image, not LCD area. If you want a 70" image, then I doubt that any 50 Watt halogen bulb will do it. Maybe the "Philips 100 Watt wide pin capsule bulb with a GY8.6 base", would be bright enough if you add a good spherical reflector behind it and a condensor lens in front of it.
I have seen some pictures of a projector where the builder used an abrasive cutting wheel to remove the base of a large dichroic reflector halogen bulb. Then he put a very small MH lamp in through the hole, to make a super projection lamp. But I think you could get just as much light out of that MH bulb with a silver-plated soup ladle behind it. Then put a hot mirror in front of it to remove the IR.
>CRT lenses that are smaller
I guess you could ask the electronics goldmine website the diameter of their TV projection lens. If that is smaller, it might work for you. I think they come in a lot of different sizes.
>50 Watt dichroic bulb
Dichroic reflectors are great, and a 15 degree beam would let you use a single lens to converge the light to the projection lens. Or maybe with a large enough lens, you wouldn't need to converge it at all. But you need a certain number of lumens per square foot of screen image, not LCD area. If you want a 70" image, then I doubt that any 50 Watt halogen bulb will do it. Maybe the "Philips 100 Watt wide pin capsule bulb with a GY8.6 base", would be bright enough if you add a good spherical reflector behind it and a condensor lens in front of it.
I have seen some pictures of a projector where the builder used an abrasive cutting wheel to remove the base of a large dichroic reflector halogen bulb. Then he put a very small MH lamp in through the hole, to make a super projection lamp. But I think you could get just as much light out of that MH bulb with a silver-plated soup ladle behind it. Then put a hot mirror in front of it to remove the IR.
Hey how do you read my thoughts !?!?!?! I was thinking about that bulb when I saw it the other day... and was also wondering if it would fit in a dichroic-type reflector...
I found this interesting contraption that I might experiment with... don't even know what it is, but it has bulb and lenses for $3, so I might as well give it a try...
It's sunny today (cold though - lucky you in CA), so I'll run some testing during daylight.
Thanks !!!
BTW, do you have any idea of what to do with a 48'' fresnel??
I was thinking about that bulb when I saw it the other day... and was also wondering if it would fit in a dichroic-type reflector...I found this interesting contraption that I might experiment with... don't even know what it is, but it has bulb and lenses for $3, so I might as well give it a try...
It's sunny today (cold though - lucky you in CA), so I'll run some testing during daylight.
Thanks !!!
BTW, do you have any idea of what to do with a 48'' fresnel??
what to do with a 48'' fresnel?
Maybe melt aluminum for doing casting? Actually, you don't have to put stuff exactly at the focal length. So you could make a solar furnace that would heat stuff as much as you wanted by adjusting the position.
I knew the specs of that halogen bulb because I have one sitting right next to my computer. I bought it to use for adjusting the optics spacing in my projector, since halogen is much better at on/off cycles than MH bulbs.
Maybe melt aluminum for doing casting? Actually, you don't have to put stuff exactly at the focal length. So you could make a solar furnace that would heat stuff as much as you wanted by adjusting the position.
I knew the specs of that halogen bulb because I have one sitting right next to my computer. I bought it to use for adjusting the optics spacing in my projector, since halogen is much better at on/off cycles than MH bulbs.
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