I don't want to jack the thread, but couldn't resist a comment. Solar is the only real answer when it comes to the future of energy. Hydrogen is a farce because the easiest way to produce it is from, you guessed it, oil. The shame is that man's ability to harness solar energy has been around for decades, yet the only device you commonly see which is solar powered are calculators.
Things are going to change though. NASA and private corporations use solar energy extensively for satellites (and in NASA's case on landers too). I don't think it'll be too long before we see people living in solar powered homes. Places like Cali are ideal for it. Then it will slowly spread into different areas. Hydrogen is just buying time for the Oil Giants.
Things are going to change though. NASA and private corporations use solar energy extensively for satellites (and in NASA's case on landers too). I don't think it'll be too long before we see people living in solar powered homes. Places like Cali are ideal for it. Then it will slowly spread into different areas. Hydrogen is just buying time for the Oil Giants.
Hooked up the 875w last night, and it made a huge difference. Before, I had to push 80-90% brightness to get a good pic, and it wouldn't wash out until 100%. Now I am at 50-60%, and to wash out, only 70%. So it is definitely an improvement. I still have to put on the 220mm fresnel (has 330mm), so it will probably be brighter still figuring loss of light by distance, and then get some sort of reflector set up. So all in all, the 875w was the way to go. You definitely have to have a lens as big as mine or bigger though. I have a 104mm wide lens, and it is about 1mm on each side too small. 4000k works ok, but it was alittle yellow, so I upped the blue and lowered the other colors. It is now perfect. As soon as I get a chance, and the money, I am gonna order a lux meter. Which is the best for our applications, and how do I exactly measure? IE: distance to the lens, wall distance from projector, size of image, etc. Thanks
hmm so u went all the way up to 875w thats cool. how big is the arc on it.
im using 1000w and the arc is about 80mm and im using the 18" beseler lens. so most of the light gets through but now all.
so im looking for a 500mm fresnel
im using 1000w and the arc is about 80mm and im using the 18" beseler lens. so most of the light gets through but now all.
so im looking for a 500mm fresnel
I was looking for info on the 1000w because it has better color, before i got this. I couldn't get a definite arc length, so I went with this. It has almost the same lumen output I think 95,000. It has a 71mm arc. Not too much smaller sounds like. I am gonna do a lumen test soon. The 550mm fresnel is what I use. i got it at 3dlens. I put it back 40mm from the actual lcd, so it makes it more like a 500mm fresnel if you understand my reasoning.
Miedosoracing said:
Can you tell us more about the 875, was that the venture? what is the fl of the triplet. I have found that the 330mm v 220mm the main gain in in the middle for thr 220mm fresnel moving from 220mm to 330mm the hot spot gets less but the rest almost stays the same.
The 220mm may give you more light spillage too but that depends on the fl og the triplet.
It would be great if you posted some pictures at LL for all of us to see.
Yes, it is the venture. here are the specs. my goal with this light is 1/2% getting to the wall. If I get that or maybe even alittle more, it will be good. http://www.venturelighting.com/LampsDataSheets/PulseStartMetalHalide/33759.pdf
As far as pics, I am waiting to be complete before I post the actual inside. I could actually close it up and say done, but I just am shooting for the best of the best. Here are pics of the actual projector. http://diyprojectorcompany.com/phpBB2/viewtopic.php?t=1672
The triplet is a home made one. I am still working on that as well. I think most likely that I will be ordering to a Pro lens from LL. People say it gives corner to corner. I am getting a good pic, but not complete corner to corner. My lens is 104mm wide with a focal length of 509mm or something pretty close to that. I have my fresnels set up to slide, so if the light is off alittle to the side, it can be slid to make it exactly in the middle. I have a lux meter ordered, so when i get that, I will post those numbers as well.
As far as pics, I am waiting to be complete before I post the actual inside. I could actually close it up and say done, but I just am shooting for the best of the best. Here are pics of the actual projector. http://diyprojectorcompany.com/phpBB2/viewtopic.php?t=1672
The triplet is a home made one. I am still working on that as well. I think most likely that I will be ordering to a Pro lens from LL. People say it gives corner to corner. I am getting a good pic, but not complete corner to corner. My lens is 104mm wide with a focal length of 509mm or something pretty close to that. I have my fresnels set up to slide, so if the light is off alittle to the side, it can be slid to make it exactly in the middle. I have a lux meter ordered, so when i get that, I will post those numbers as well.
Everyone so far has loved the pro lens. It is a 500mm fl so your throw will not change.
If you move the lamp closer to the fresnel the light at the triplet will grow larger soon it will no longer all fit in the lens and will spill over. any light that does not make it into the lens will not go to the screen.
The two fresnels focus the light judt like a camera from the lamp to the triplet. It realy makes a image of the lamp arc so that is what I will call it for now.
The shorter the rear fresnel the larger the arc image is at the triplet. The lamp arc image will increass with a shorter rear fresnel. I made a list over at LL. it is real easy. a larger lens lets you use a larger lamp.
For a 220mm fresnel the largest lamp arc image that will fit is 44mm. For a 330mm fresnel it is 66mm so for your setup and the pro lens Iwould stay with the 330mm.
I have done a lot of real life testing with both fresnels and the main differance in brightness in mainly in the center. The 220mm is a lot brighter in the middle. The light is a lot more even with a 330mm.
This effect will be less with a 15" lcd.
If you run the 550mm/330mm fresnels then with the pro lens you may end up with a 280mm or so lamp to fresnel distance which is a nice compromize.
Your setup would be brighter with the 135mm triplet from diypc or a buhl 18" fl lens. The focus is almost perfect on a 15" lcd and you could run a 220mm fresnel and all the light will fit in the triplet.
If you end up running the 220mm you will have heat to deal with so a heat sheild will be needed mabey heat glass rather than Lexan.
If you move the lamp closer to the fresnel the light at the triplet will grow larger soon it will no longer all fit in the lens and will spill over. any light that does not make it into the lens will not go to the screen.
The two fresnels focus the light judt like a camera from the lamp to the triplet. It realy makes a image of the lamp arc so that is what I will call it for now.
The shorter the rear fresnel the larger the arc image is at the triplet. The lamp arc image will increass with a shorter rear fresnel. I made a list over at LL. it is real easy. a larger lens lets you use a larger lamp.
For a 220mm fresnel the largest lamp arc image that will fit is 44mm. For a 330mm fresnel it is 66mm so for your setup and the pro lens Iwould stay with the 330mm.
I have done a lot of real life testing with both fresnels and the main differance in brightness in mainly in the center. The 220mm is a lot brighter in the middle. The light is a lot more even with a 330mm.
This effect will be less with a 15" lcd.
If you run the 550mm/330mm fresnels then with the pro lens you may end up with a 280mm or so lamp to fresnel distance which is a nice compromize.
Your setup would be brighter with the 135mm triplet from diypc or a buhl 18" fl lens. The focus is almost perfect on a 15" lcd and you could run a 220mm fresnel and all the light will fit in the triplet.
If you end up running the 220mm you will have heat to deal with so a heat sheild will be needed mabey heat glass rather than Lexan.
Thanks for your reply. I have talked with Alan at the diyprocomp and have decided to go that direction. He is working on getting it done with a 500mm focal. That will be the perfect lens for me then, because the size of my light. I actually already switched the fresnel to the 220 this weekend. Although I figured some things out. I was getting quite a few bright spots with the 330mm. I figured out it was not lined up perfectly. When I put the 220 on, I could see where the bright spots were, when I put it up to a light. So I moved the 550 and 220 together around, and got it without those. Then I tested it on the projector, and was correct. I now do not have those. So, that should give me a good balance. The 135mm wide triplet, 500mm fl, and the 875w light. And yes, I did notice a large difference in light spillage when I went to the 220. So, it is definitely not as bright right now, but when I can accept the full arc, I should be good to go. Thanks again.
Oh, bye the way. I have no heat issues still. I have 2 120mm fans, and one cylindrical fan on the lcd. Also the lcd has chrome AG, which could be a reason for keeping it cool. Maybe it is some sort of cold mirror?? But I do run a UV plastic, and a Low E glass from Home depot. I also lined the box with aluminum foil. I do believe if I went with the 1500w light I originally planned, I would be dealing with issues, but for now, the 875w doesn't get hot for me.
Oh, bye the way. I have no heat issues still. I have 2 120mm fans, and one cylindrical fan on the lcd. Also the lcd has chrome AG, which could be a reason for keeping it cool. Maybe it is some sort of cold mirror?? But I do run a UV plastic, and a Low E glass from Home depot. I also lined the box with aluminum foil. I do believe if I went with the 1500w light I originally planned, I would be dealing with issues, but for now, the 875w doesn't get hot for me.
Miedosoracing, I wanted to say your projector looks great! I did comment before on DIYPC but I wanted to say it again here.
You might want to try messing with reflectors and their placement. You can adjust it from a spotlight-like beam to a more spread beam. That might help with your corner darkness. Also, moving the bulb around will help with corner darkness; but I'm sure you've already done this.
I agree that a wider proj lens will make the screen brighter. If you are using a 15" LCD (can't remember), an 18" opaque lens will cover it clearly. The 135mm from DIYPC will too and so will the pro lens from LL. With your arc size, I wouldn't go with the 80mm lenses being sold.
Good luck on your ventures!
You might want to try messing with reflectors and their placement. You can adjust it from a spotlight-like beam to a more spread beam. That might help with your corner darkness. Also, moving the bulb around will help with corner darkness; but I'm sure you've already done this.
I agree that a wider proj lens will make the screen brighter. If you are using a 15" LCD (can't remember), an 18" opaque lens will cover it clearly. The 135mm from DIYPC will too and so will the pro lens from LL. With your arc size, I wouldn't go with the 80mm lenses being sold.
Good luck on your ventures!
Thanks, I really appreciate it. yeah, I have made a reflector that got rid of the corner darkness. (did some cutting on a target 5" bowl. It seems to be pretty even throughout, according to my digital camera. But we will soon know when I lux meter it. I am almost there. All I have left to do, is get the lens either made or bought, and I will have a complete projector that I can use for many years. I really hope to get over the 500 lumen mark. Then I can say I accomplished what I wanted. As far as commercial units. I have paid 3 times that (I've made multiple pj's). So to the people who shun me for it, they just don't understand. It isn't about the money, we can all make more. It is about pride, accomplishment, and honor.😉
Oh yeah, 15" lcd, but the wide screen one.
Oh yeah, 15" lcd, but the wide screen one.
Now I'm just getting confused
Preface:
I've been lurking for a month, have read a zillion posts. I have searched, researched, read some more, and then some more. Right now, I am aquiring my parts, and learning the design theory and the variables. I'm not up to the numbers, lumens, luxometer measurements and so on....really just looking at the physics and logistics of the light collection, and path of the light to get the LCD lit up bright and even.
I'm now up to a reflector, and was researching a real-time ray tracing optics webpage.
Well, try this on for size:
http://webphysics.davidson.edu/Course_Material/Py230L/optics/lenses.htm
It's a cool little Java applet that lets you move your elements around, change focal lengths, etc...in real time.
Insert your LCD in your mind wherever you make your parallel lines happen.
So here's a source point light source, and one lens focused on the light. Parallel light rays result:
My confusion comes in here.
Consider the "common" method all over this site and others....TRUE spherical reflector, light arc at the focal point to reflect back-through the arc, then out to a focused fresnel:
The amount of light rays that would hit the LCD parallel seem like NOTHING compared to the amount of light thrown at the LCD by using just the reflector (no collection fresnal), moving the light closer to the back of the reflector, and using the reflector itself to collect and straighten out the rays:
Here's the direct rays thrown back in the diagram for comparison...like 25% worth it seems:
Why would I want to use the first method? The amount of rays actually fitting into the focal point end of the fresnels "view" would even seem to dictate that the reflector could be small, basically just behind the arc.
Doesn't a large reflector, with straight rays resulting, seem to be an overwhelmingly vast difference, and much brighter?
So of course I assume this has been discussed before, I think I've read some on it, but I'll be damned if I have the time to go looking. Hopefully my pretty pictures show effort to contibute and inquire enough that this won't just get a response stating to go search.
Thanks . These threads have been invaluable.
Preface:
I've been lurking for a month, have read a zillion posts. I have searched, researched, read some more, and then some more. Right now, I am aquiring my parts, and learning the design theory and the variables. I'm not up to the numbers, lumens, luxometer measurements and so on....really just looking at the physics and logistics of the light collection, and path of the light to get the LCD lit up bright and even.
I'm now up to a reflector, and was researching a real-time ray tracing optics webpage.
Well, try this on for size:
http://webphysics.davidson.edu/Course_Material/Py230L/optics/lenses.htm
It's a cool little Java applet that lets you move your elements around, change focal lengths, etc...in real time.
Insert your LCD in your mind wherever you make your parallel lines happen.
So here's a source point light source, and one lens focused on the light. Parallel light rays result:
My confusion comes in here.
Consider the "common" method all over this site and others....TRUE spherical reflector, light arc at the focal point to reflect back-through the arc, then out to a focused fresnel:
The amount of light rays that would hit the LCD parallel seem like NOTHING compared to the amount of light thrown at the LCD by using just the reflector (no collection fresnal), moving the light closer to the back of the reflector, and using the reflector itself to collect and straighten out the rays:
Here's the direct rays thrown back in the diagram for comparison...like 25% worth it seems:
Why would I want to use the first method? The amount of rays actually fitting into the focal point end of the fresnels "view" would even seem to dictate that the reflector could be small, basically just behind the arc.
Doesn't a large reflector, with straight rays resulting, seem to be an overwhelmingly vast difference, and much brighter?
So of course I assume this has been discussed before, I think I've read some on it, but I'll be damned if I have the time to go looking. Hopefully my pretty pictures show effort to contibute and inquire enough that this won't just get a response stating to go search.
Thanks . These threads have been invaluable.
Your numbers are right. It's the implementation that is difficult.
Most commercial projectors use a parabola and light setup that you showed in your second setup. There setup is designed from the ground up to maximize light output. However, for us the size of the lcd requires us to have an extremely large parabola and I think lengthens the distance to the lcd. Also, in experiments at LL with that setup there was usually a dark spot in the middle of the screen, caused by the lightbulb. When the experimenter played with distances he was able to minimize the dark spot.
However, to my knowledge, no one has been able to successfully implement the second setup design successfully in a working projector. If you find a way then it would be extrememly valuable to DIY projector builders the world over.
Most commercial projectors use a parabola and light setup that you showed in your second setup. There setup is designed from the ground up to maximize light output. However, for us the size of the lcd requires us to have an extremely large parabola and I think lengthens the distance to the lcd. Also, in experiments at LL with that setup there was usually a dark spot in the middle of the screen, caused by the lightbulb. When the experimenter played with distances he was able to minimize the dark spot.
However, to my knowledge, no one has been able to successfully implement the second setup design successfully in a working projector. If you find a way then it would be extrememly valuable to DIY projector builders the world over.
The diagrams drawn by NoSloppy show single point light source whereas in practice such source is non-existent. The multiple point source give rise to light rays emanating in different directions. Further the enclosure of the light source cause numerous reflections making the beam of light rays in different directions. We got excellent results in our projector, the details of which can be seen in our web page. After grasping the theory, we experimented and found the most optimum results by suitable adjustments. Theory provides guidance but actual practice alone will provide near perfect results.
Well, in the construction process, I plan on leaving the reflector for last, and before I finalize and screw things down, I'll certainly try:
Large reflector -> bulb -> ir glass -> uv glass -> LCD -> Fresnel -> Projection lens.
I'm talking like a reflector that fills the whole box - something like a 15" diamater mixing bowl:
http://www.foodservicedirect.com/largeView.cfm?pic=dcsbl13dl.jpg
Large reflector -> bulb -> ir glass -> uv glass -> LCD -> Fresnel -> Projection lens.
I'm talking like a reflector that fills the whole box - something like a 15" diamater mixing bowl:
http://www.foodservicedirect.com/largeView.cfm?pic=dcsbl13dl.jpg
Ok , first of all sorry about the double post - i attempted to edit by going back, but that resulted in a duplicate post . I will kill it as soon as I see edit and delete buttons. I am a brand new registree.
During lunch I went to Target and picked up a perfectly spherical 5.30" "medium prep bowl". The surface is mirror, unlike some other candidates which had a radial polished appearance..dull and non reflective.
I disassembled a little halogen desklamp, taped the bulb and wire to a pen, and experimented with the focal lenghs using my desk as a target.
I held the bulb about 1" from the desk surface, then lowered the bowl. First I got a fine point of reflected concentrated light as the bulb reached the opening of the bowl (r/2) as in example 1 above (2nd pic)
Then as I sunk the bulb closer in to the concave surface, it did indeed spread out. A parabolic effect as in example 2 above. (3rd pic)
So sort of answering my own question by seeing my test results, I believe the following:
Although many more rays may be directed at the LCD using the parabolic reflector method, they are not as bright as the concentrated point. Magnifying the very bright concentration is most likely going to be brighter. I appreciate an audience for my question, and the responses.
Thanks again.
During lunch I went to Target and picked up a perfectly spherical 5.30" "medium prep bowl". The surface is mirror, unlike some other candidates which had a radial polished appearance..dull and non reflective.
I disassembled a little halogen desklamp, taped the bulb and wire to a pen, and experimented with the focal lenghs using my desk as a target.
I held the bulb about 1" from the desk surface, then lowered the bowl. First I got a fine point of reflected concentrated light as the bulb reached the opening of the bowl (r/2) as in example 1 above (2nd pic)
Then as I sunk the bulb closer in to the concave surface, it did indeed spread out. A parabolic effect as in example 2 above. (3rd pic)
So sort of answering my own question by seeing my test results, I believe the following:
Although many more rays may be directed at the LCD using the parabolic reflector method, they are not as bright as the concentrated point. Magnifying the very bright concentration is most likely going to be brighter. I appreciate an audience for my question, and the responses.
Thanks again.
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