I found this MH bulb with 15 degree beam and am thinking of trying this out. Looks like the bulb has internal reflector and a small condensor like set up on the top which spreads light at 15 degree beam. Unfortunately no other data- physical measurement etc. found on the site. Any suggestions?
Link:
http://www.lighting.philips.com/nam/product_database/hid/displayhid.php?id=125
Link:
http://www.lighting.philips.com/nam/product_database/hid/displayhid.php?id=125
Attachments
This bulb is huge; 10-7/8" long and 7-1/2" wide:
http://www.donsbulbs.com/cgi-bin/r/b.pl/mh400rsp.html
http://www.lighting.philips.com/nam/product_database/pdf/hid.pdf
I'm trying the MH175/RSP. I just got the bulb this week, but my ballast turned out to be bad, so I have to wait another 2 weeks to get a replacement.
http://www.donsbulbs.com/cgi-bin/r/b.pl/mh400rsp.html
http://www.lighting.philips.com/nam/product_database/pdf/hid.pdf
I'm trying the MH175/RSP. I just got the bulb this week, but my ballast turned out to be bad, so I have to wait another 2 weeks to get a replacement.
Where can I buy MH175/RSP ?
Yes...its huge I found out when I searched on philips PDF files. I like MH175/RSP that you have..Looks perfect size for my project.
donsbulbs ran out of it do you suggest any other place where I can buy this bulb?
Rajkumar
Yes...its huge I found out when I searched on philips PDF files. I like MH175/RSP that you have..Looks perfect size for my project.
donsbulbs ran out of it do you suggest any other place where I can buy this bulb?
Rajkumar
http://www.atlantalightbulbs.com/
$89, but that's about as good as you'll get. I know they have them in stock, because they had to order a case to get the one bulb I ordered =)
This is a 16deg lamp. They have a flood version that's $20 cheaper. I went with the 16deg lamp, because I figured a more tightly focused beam would mean more light directed out the apeture. I hope.
$89, but that's about as good as you'll get. I know they have them in stock, because they had to order a case to get the one bulb I ordered =)
This is a 16deg lamp. They have a flood version that's $20 cheaper. I went with the 16deg lamp, because I figured a more tightly focused beam would mean more light directed out the apeture. I hope.
Ballast for MH 175 bulb
Thanks for the bulb suggestions. I will order it soon..looks great. Is it true that its rated for 60k lumens!! (on the weblink you gave). Thats really bright so even if we dont capture a whole lot of light we sould be fine..
Which ballast are you using. I am thinking of buying IceCap electronic ballast which can run "any" 175 w bulb at the following for $115 - that the cheapest I found. Any suggestions?
http://www.aquatictech.com/lighting.html
Thx.
Thanks for the bulb suggestions. I will order it soon..looks great. Is it true that its rated for 60k lumens!! (on the weblink you gave). Thats really bright so even if we dont capture a whole lot of light we sould be fine..
Which ballast are you using. I am thinking of buying IceCap electronic ballast which can run "any" 175 w bulb at the following for $115 - that the cheapest I found. Any suggestions?
http://www.aquatictech.com/lighting.html
Thx.
I went with a non-electronic ballast, 'cause it's so much cheaper ($40) :
BS/MH0175MT
http://www.1000bulbs.com/
(enter the part # in the search box)
It's a little harder to wire up, and a tiny bit noisier, but I got burned with a bad electronic Magnatek M57 ballast off ebay, so I needed a cheap solution. Esp. after laying out $80 for the bulb.
Not gonna be here til 02DEC, tho...
BS/MH0175MT
http://www.1000bulbs.com/
(enter the part # in the search box)
It's a little harder to wire up, and a tiny bit noisier, but I got burned with a bad electronic Magnatek M57 ballast off ebay, so I needed a cheap solution. Esp. after laying out $80 for the bulb.
Not gonna be here til 02DEC, tho...
Also, AFAIK, the output is, indeed, 60K (peak). There is a pdf on the Philips site listing the bulb properties that supports this. However, there is probably a warm-up time before it gets to peak output. Usually not more than a few minutes.
I've become a little concerned that the 16deg beam may be a little _too_ tight. I've been toying with feeding different lights thru the optics of an OHP, and with a tight beam you lose the sharp edges of the projected image.
This is, of course, speculation until I get the ballast and can test it.
I've become a little concerned that the 16deg beam may be a little _too_ tight. I've been toying with feeding different lights thru the optics of an OHP, and with a tight beam you lose the sharp edges of the projected image.
This is, of course, speculation until I get the ballast and can test it.
Lamp to LCD distance measurements
I was wondering about the same over the weekend. I found the following formula to measure the distance between the lamp and LCD panel based on the beam angle of the bulb. I am not good at solving these kinds of equations so need some help. Here is the link and the formula. My LCD panel is 10.4 diagonal and considering the 16 degree beam angle I came up with 37 inch distance between LCD and LAMP (if I did the correct math) - Thats too far but I think a frasnel lens can be used - dont know what kind though! Any help appreciated.
http://www.highend.com/news/lightingfaq.html
I was wondering about the same over the weekend. I found the following formula to measure the distance between the lamp and LCD panel based on the beam angle of the bulb. I am not good at solving these kinds of equations so need some help. Here is the link and the formula. My LCD panel is 10.4 diagonal and considering the 16 degree beam angle I came up with 37 inch distance between LCD and LAMP (if I did the correct math) - Thats too far but I think a frasnel lens can be used - dont know what kind though! Any help appreciated.
http://www.highend.com/news/lightingfaq.html
Attachments
My calculator doesnt have an arctan button. You could look at it as half the 16deg triangle and just use
tan(alpha) = OP/ADJ
Since you want ADJ (your 'L' in the diagram),
ADJ = OP/tan(alpha)
or
ADJ = 5.2/0.14054 = 36.9999
So you're right.
A fresnel lens essentially takes light and gets it all moving in the same direction to make a narrower beam:
<img src ="http://www.lanternroom.com/fresnel/_images/fresnel02.jpg">
(the image is of a curved lighthouse fresnel, but you get the idea).
So there may be a problem with this 16deg lamp being too narrow. I don't know about that, tho, because the light source for my OHP passes it's light thru a 1.25" apeture, so there's obviously something else going on.
In any event (for me, anyway), I already have the bulb and am just waiting for the ballast so I can test it. I will post the result as soon as I have it. Worst case is I have to buy the 50deg flood, which, in your case, would reduce your depth to 11.58". This actually sounds much more sane for OHP optics, which is what most of the projectors around here are based on.
tan(alpha) = OP/ADJ
Since you want ADJ (your 'L' in the diagram),
ADJ = OP/tan(alpha)
or
ADJ = 5.2/0.14054 = 36.9999
So you're right.
A fresnel lens essentially takes light and gets it all moving in the same direction to make a narrower beam:
<img src ="http://www.lanternroom.com/fresnel/_images/fresnel02.jpg">
(the image is of a curved lighthouse fresnel, but you get the idea).
So there may be a problem with this 16deg lamp being too narrow. I don't know about that, tho, because the light source for my OHP passes it's light thru a 1.25" apeture, so there's obviously something else going on.
In any event (for me, anyway), I already have the bulb and am just waiting for the ballast so I can test it. I will post the result as soon as I have it. Worst case is I have to buy the 50deg flood, which, in your case, would reduce your depth to 11.58". This actually sounds much more sane for OHP optics, which is what most of the projectors around here are based on.
Beam angle for MH 175 RFL
I am glad my numbers were correct! The problem with MH 175 RFL(Flood) is that its not as bright as the RSP (10 K lumen v.s. 60K) but the beam angle is 65 so the distance I calculated is around 9.16 inch which will work out best sizewise. Since most of the 10K lumens are actually usable I dont think it will be a huge problem for the brightness.
I am planning on cutting the bottom my spare OHP and see if I can mount the lamp upright in a small enclosure before building a custom box.
I am glad my numbers were correct! The problem with MH 175 RFL(Flood) is that its not as bright as the RSP (10 K lumen v.s. 60K) but the beam angle is 65 so the distance I calculated is around 9.16 inch which will work out best sizewise. Since most of the 10K lumens are actually usable I dont think it will be a huge problem for the brightness.
I am planning on cutting the bottom my spare OHP and see if I can mount the lamp upright in a small enclosure before building a custom box.
Yeah, that was kinda why I went with the 16deg; that, and I was laboring under the (maybe false) assumption that I wanted the light in a tight beam to begin with.
Seeing as I had planned to mount this new light source on an existing OHP, I hope that my distance does not need to be 37". I'm gonna give the 16deg bulb a chance. After that, I'm either going to have to use a lens to spread the beam, or design a rear-facing mount and cold mirror setup to increase the bulb-to-stage distance (eg hack it up), or give it up and use the bulb to **** off my backyard neighbors instead.
If this fails, I will probably try the "wider pipe" approach with an unfocused 400W MH; I had my eye on the $90 rig that some guy builds and sells on ebay. It would be a tight fit on the back of the OHP, but it would probably pump out enough light to overcome the problem.
Seeing as I had planned to mount this new light source on an existing OHP, I hope that my distance does not need to be 37". I'm gonna give the 16deg bulb a chance. After that, I'm either going to have to use a lens to spread the beam, or design a rear-facing mount and cold mirror setup to increase the bulb-to-stage distance (eg hack it up), or give it up and use the bulb to **** off my backyard neighbors instead.
If this fails, I will probably try the "wider pipe" approach with an unfocused 400W MH; I had my eye on the $90 rig that some guy builds and sells on ebay. It would be a tight fit on the back of the OHP, but it would probably pump out enough light to overcome the problem.
MH lamps sold in cases only
Placed an order with atlantalightbulbs.com for the RFL lamps and they said its out of the stock and will take 2 weeks or more time to get it...They do have RSP (16o beam) in stock (since they order a case for your order) and am curious to see how it works out for you..
I also checked my 3M (model ?) OHP and the light is mounted on the back side wall in a separate compartment with a 1 1/2 inch opening pointed down diagonally at a cold mirror which bounces it to the OHP stage. Similar arrangement might work with a narrow beam MH RSP lamp that you have since the halogen light is going through a 1 1/2 inch aparture and its spread evenly on the OHP stage. So I am back to the idea of using the lamp you have - even if I cant use all the available 60K lumens, I should be fine with what ever passes through that 1 1/2 inch aparture..
I also found the GE made MH bulb with elliptical syle reflector with up to 9K lumens still unable to loacate an online dealer.. Here is the link:
http://www.gelighting.com/na/business/pl3_hid_cmh.html
- I tried my LCD panel Z255, 800 X 600 16 M color, on a regular 3M overhead with 360W Helogen bulb and was able to get a corner to corner crisp and balanced image and was very happy (and so was my wife!). I watched a DVD last night and it was fun. I am using XGA theater TV4000 from avtoolbox where you can change the resolution from 480 x 600 to 800 x 600 with a remote and can adjust brighness, etc too. The panel has built in Hi-Fi speaker which was enought for a trial run. I need to figure out how to make the fan on the panel quieter...
So I think MH RSP lamp should work with a narrow beam even without using any thing to spread the light - just by bouncing it off a cold mirror. Did you do any more tests with your OHP set up?
thx.
Placed an order with atlantalightbulbs.com for the RFL lamps and they said its out of the stock and will take 2 weeks or more time to get it...They do have RSP (16o beam) in stock (since they order a case for your order) and am curious to see how it works out for you..
I also checked my 3M (model ?) OHP and the light is mounted on the back side wall in a separate compartment with a 1 1/2 inch opening pointed down diagonally at a cold mirror which bounces it to the OHP stage. Similar arrangement might work with a narrow beam MH RSP lamp that you have since the halogen light is going through a 1 1/2 inch aparture and its spread evenly on the OHP stage. So I am back to the idea of using the lamp you have - even if I cant use all the available 60K lumens, I should be fine with what ever passes through that 1 1/2 inch aparture..
I also found the GE made MH bulb with elliptical syle reflector with up to 9K lumens still unable to loacate an online dealer.. Here is the link:
http://www.gelighting.com/na/business/pl3_hid_cmh.html
- I tried my LCD panel Z255, 800 X 600 16 M color, on a regular 3M overhead with 360W Helogen bulb and was able to get a corner to corner crisp and balanced image and was very happy (and so was my wife!). I watched a DVD last night and it was fun. I am using XGA theater TV4000 from avtoolbox where you can change the resolution from 480 x 600 to 800 x 600 with a remote and can adjust brighness, etc too. The panel has built in Hi-Fi speaker which was enought for a trial run. I need to figure out how to make the fan on the panel quieter...
So I think MH RSP lamp should work with a narrow beam even without using any thing to spread the light - just by bouncing it off a cold mirror. Did you do any more tests with your OHP set up?
thx.
I also have a 3M OHP with the same light setup. I'm just worried that the beam spread might not be enough.
Also, I examined the bulb that goes in the OHP, and IMHO it appears to be an ellipsoid reflector. That has a great deal of bearing on what we're doing:
http://ourworld.compuserve.com/homepages/awi_industries/Optic_reflectors.htm
If it is indeed an elipsoid, then the 1" apeture in front of the light is probably roughly at the focal point of the beam. Then the beam reverses itself and spreads out.
With our parabolics, there would be no need for this apeture. On the down side, the beam may be too tight and not spread out enough to cover the entire LCD. Or, it might enter the fresnel at a different angle than the original light source, and therefore throw off the final image. I think that this could be remedied with a simple spreader lens, but I don't know. I have a number of lenses that I got in a parts auction, so hopefully I can spread the beam if it proves to be too tight.
(std OHP optics sans various mirrors)
<img src="http://members.cox.net/rolm/images/ohp_optics.jpg">
<OHP optics with a parabolic light source)
<img src="http://members.cox.net/rolm/images/ohp_optics2.jpg">
The pictures suck, but you'll probably get the idea: if the beam angle coming out of the light source in the lower image is not broad enough (or does not spread enough), it could be fed thru a lens to broaden it.
I dunno, this is all academic until I can build the new light source and feed it thru the OHP.
Also, I examined the bulb that goes in the OHP, and IMHO it appears to be an ellipsoid reflector. That has a great deal of bearing on what we're doing:
http://ourworld.compuserve.com/homepages/awi_industries/Optic_reflectors.htm
If it is indeed an elipsoid, then the 1" apeture in front of the light is probably roughly at the focal point of the beam. Then the beam reverses itself and spreads out.
With our parabolics, there would be no need for this apeture. On the down side, the beam may be too tight and not spread out enough to cover the entire LCD. Or, it might enter the fresnel at a different angle than the original light source, and therefore throw off the final image. I think that this could be remedied with a simple spreader lens, but I don't know. I have a number of lenses that I got in a parts auction, so hopefully I can spread the beam if it proves to be too tight.
(std OHP optics sans various mirrors)
<img src="http://members.cox.net/rolm/images/ohp_optics.jpg">
<OHP optics with a parabolic light source)
<img src="http://members.cox.net/rolm/images/ohp_optics2.jpg">
The pictures suck, but you'll probably get the idea: if the beam angle coming out of the light source in the lower image is not broad enough (or does not spread enough), it could be fed thru a lens to broaden it.
I dunno, this is all academic until I can build the new light source and feed it thru the OHP.
How to spread light..
I could not find any online source for the flood style (RFL) MH 175 W so far so am thinking of buying the RSP lamp like yours and work on spreading the tight beam. Looking for suggestions on how to spread that 16o beam using some sort of lense. While reading online on how the beam angle is measured I found out that the beam angle is spread from center to the edge where the light intensity is 50% of the center. If that's the case than we may end up with a hotspot issue. (see drawing).
Also, how about using a magnifying mirror (cheap $10 used for makeup) which may be able to bounce and spread light at the same time which may reduce the length of the light path.
I am very curious to see your results when you get the ballast and test the lamp. I am still waiting for the reply from GE regarding their MH 100 watt lamp with elliptical reflector. I will post the link on that lamp later today.
I could not find any online source for the flood style (RFL) MH 175 W so far so am thinking of buying the RSP lamp like yours and work on spreading the tight beam. Looking for suggestions on how to spread that 16o beam using some sort of lense. While reading online on how the beam angle is measured I found out that the beam angle is spread from center to the edge where the light intensity is 50% of the center. If that's the case than we may end up with a hotspot issue. (see drawing).
Also, how about using a magnifying mirror (cheap $10 used for makeup) which may be able to bounce and spread light at the same time which may reduce the length of the light path.
I am very curious to see your results when you get the ballast and test the lamp. I am still waiting for the reply from GE regarding their MH 100 watt lamp with elliptical reflector. I will post the link on that lamp later today.
Attachments
I actually just got done wiring up my test kit and running some initial tests for the lamp.
The bad news is that you are right: this bulb has a terrific hotspot at the center. In side-by-side comparison, it at first appears that the MH bulb is putting out about as much light as the 360w halogen in the OHP. But if you look closer, you can see that there is a brilliant hotspot that is about 4" diameter at 6'. This, I am sure, is where they measured the 60K lumens. If we could come up with a lens to spread this hotspot, then this might be a viable solution.
I also experimented with some masks for the bulb, and came to the conclusion that the beam, as it emanates from the bulb, is just too narrow for us to use.
My last experiment was to direct the bulb thru the optics of the OHP. This cinched it: there was one hotspot at the center of the image, and dim light around the prerimeter.
The bulb appears to put out a phenomenal amount of light for it's wattage, but I don't think it's usable without mucking with the beam.
I took images with my digital camera, but the hotspot was so bright as to interfere with the image. I'll give you an example: the attached image is one where the OHP and the MH are side-by-side. The horizontal lines are interference.
<img src="http://members.cox.net/rolm/images/sidebyside.jpg">
Your mirror idea may work, but my approach (at least) was to leave as much of the internals of the OHP alone and instead to alter the light source.
I'm going to experiment with some of my lenses tonight to see if I can spread the beam a little more.
Note to self: wear sunglasses when messing around with this light. I came upstairs 2 hours ago and I still have spots in front of my eyes...
The bad news is that you are right: this bulb has a terrific hotspot at the center. In side-by-side comparison, it at first appears that the MH bulb is putting out about as much light as the 360w halogen in the OHP. But if you look closer, you can see that there is a brilliant hotspot that is about 4" diameter at 6'. This, I am sure, is where they measured the 60K lumens. If we could come up with a lens to spread this hotspot, then this might be a viable solution.
I also experimented with some masks for the bulb, and came to the conclusion that the beam, as it emanates from the bulb, is just too narrow for us to use.
My last experiment was to direct the bulb thru the optics of the OHP. This cinched it: there was one hotspot at the center of the image, and dim light around the prerimeter.
The bulb appears to put out a phenomenal amount of light for it's wattage, but I don't think it's usable without mucking with the beam.
I took images with my digital camera, but the hotspot was so bright as to interfere with the image. I'll give you an example: the attached image is one where the OHP and the MH are side-by-side. The horizontal lines are interference.
<img src="http://members.cox.net/rolm/images/sidebyside.jpg">
Your mirror idea may work, but my approach (at least) was to leave as much of the internals of the OHP alone and instead to alter the light source.
I'm going to experiment with some of my lenses tonight to see if I can spread the beam a little more.
Note to self: wear sunglasses when messing around with this light. I came upstairs 2 hours ago and I still have spots in front of my eyes...
beam too narrow...
Rolm,
I was very anxious to find out the test results and am disappointed to know that the beam is too narrow for our use (atleast without too many optics involved) and the hotspot is an issue.. 60K lumens is indeed illusive as I originally suspected. Well, I will have to try with the Flood style lamp (still unable to find online!) and post the test results..
If I cant find the MH 175 RFL lamp by the end of today, i am going to get two MH 100 W lamps from bulbs.com (Flood style with 60o beam) and use it with a dual MH ballast (used in growlight set up) and see if I can use two lamps with some sort of mirror arrangement to bounce light to the LCD. I am working on the drawing rightnow.
I also found this interesting setup for auto headlight with elliptical reflector and am looking for the sources to find/buy this. Here is the link (page six center diagram)
http://www.osram.se/pdf/produktblad/Xenarc.pdf
Rolm,
I was very anxious to find out the test results and am disappointed to know that the beam is too narrow for our use (atleast without too many optics involved) and the hotspot is an issue.. 60K lumens is indeed illusive as I originally suspected. Well, I will have to try with the Flood style lamp (still unable to find online!) and post the test results..
If I cant find the MH 175 RFL lamp by the end of today, i am going to get two MH 100 W lamps from bulbs.com (Flood style with 60o beam) and use it with a dual MH ballast (used in growlight set up) and see if I can use two lamps with some sort of mirror arrangement to bounce light to the LCD. I am working on the drawing rightnow.
I also found this interesting setup for auto headlight with elliptical reflector and am looking for the sources to find/buy this. Here is the link (page six center diagram)
http://www.osram.se/pdf/produktblad/Xenarc.pdf
Yeah, after further experimentation I think I have to call the MH175/RSP a bust. I was able to spread the hotspot using a 2x5 glass fresnel, but that showed me that there was an anomoly in the bulb on one side, resulting in a serious color difference. This anomoly is most likely a result of the inner workings of the bulb (the elements used to create the arc).
Mocking it up on the OHP, I was able to get about the same image brightness as with the 360w halogen bulb. About as bright, but uneven and dim around the edges.
My next move is to try to adapt a higher-wattage non-PAR bulb. I ordered a 400w Mh with a 16" x 8" reflector. I plan to polish the reflector and probably try removing the inner light stage from the OHP to move as much light as possible.
Another idea was to take a page from uvodee and try installing multiple fluorex bulbs. Admittedly, the light is about as unpolarized as you can get, but if you can generate enough of it you might be able to overcome that.
Either concept is going to cost about $100 to try out. I've already blown about $150 on bulb, ballast(s) and shipping, and I'm back to square one.
Ellipsoidal reflectors are most likely the way to go with this, but the difficulty lies in the size: either a reflector that's large enough to use a std MH bulb, or a MH bulb that's small enough (and affordable) to fit a common ellipsoidal reflector. I've seen docs similar to the one you linked, but the xenon bulbs don't put out enough light for our purposes, and MH bulbs small enough to fit that reflector are either limited to 150 watts or are very expensive. In any event, they would be one-ended bulbs, and probably suffer from the same anomoly as the PAR bulb that I have now.
As a side note, this is one of the reasons that production LCD projector bulbs are so expensive. MHs are great for pumping out huge amounts of light for not much watts, but getting a clean, focused beam out of them is hard by itself, and even harder as you make the bulb smaller.
I think that the answer will either lie in figuring out how to get a semi-focused beam from a common (read: cheap) ~400w bulb, or from using double-ended HQI bulbs (which are expensive).
Mocking it up on the OHP, I was able to get about the same image brightness as with the 360w halogen bulb. About as bright, but uneven and dim around the edges.
My next move is to try to adapt a higher-wattage non-PAR bulb. I ordered a 400w Mh with a 16" x 8" reflector. I plan to polish the reflector and probably try removing the inner light stage from the OHP to move as much light as possible.
Another idea was to take a page from uvodee and try installing multiple fluorex bulbs. Admittedly, the light is about as unpolarized as you can get, but if you can generate enough of it you might be able to overcome that.
Either concept is going to cost about $100 to try out. I've already blown about $150 on bulb, ballast(s) and shipping, and I'm back to square one.
Ellipsoidal reflectors are most likely the way to go with this, but the difficulty lies in the size: either a reflector that's large enough to use a std MH bulb, or a MH bulb that's small enough (and affordable) to fit a common ellipsoidal reflector. I've seen docs similar to the one you linked, but the xenon bulbs don't put out enough light for our purposes, and MH bulbs small enough to fit that reflector are either limited to 150 watts or are very expensive. In any event, they would be one-ended bulbs, and probably suffer from the same anomoly as the PAR bulb that I have now.
As a side note, this is one of the reasons that production LCD projector bulbs are so expensive. MHs are great for pumping out huge amounts of light for not much watts, but getting a clean, focused beam out of them is hard by itself, and even harder as you make the bulb smaller.
I think that the answer will either lie in figuring out how to get a semi-focused beam from a common (read: cheap) ~400w bulb, or from using double-ended HQI bulbs (which are expensive).
point source light - ellipsoidal reflector
After spending several hours to read the forum I have concluded the following:
1. Point source light (Fluorex are not suitable even if you have two of them - other people have tried them with not so impressive results)
2. Ellipsoidal reflector to focus all the light and redistribute evenlly on the panel
3. MH 250W+ is the start point higher W is better if heat issues can be resolved (Low E glass barrier, Fans, etc.)
4. Line doubler or similar device helps (I have tv 4000 and my test results shows excellent sharp image at 800 X 600 resolution (Nview z255 panel). Also, TV 4000 has a remote which helps to change brighness/contrast etc while watching movies. I show pre-recorded Alias from my VCR yesterday on 6 X 6 Da Lite screen last night (with lights off in living room) and after adjusting brightness etc.. My wife and I were very happy with the image quality. Than we played a DVD in wide screen format and it was awsome.
5. Based on the room dimension, OHP optic may not be suitable. I had to put my OHP at about 10 feet to get the image to fit on my 6 X 6 screen. I need atleast a 15 feet throw distance to get the similar size projection so am looking for some lenses.
What bulb/reflector you are looking into? 16 X 8 reflector sound a little big but still manageable. Is it ellipsoidal or parabolic? I have a friend who is into glass blowing and I talked to her yesterday she can make a reflector from glass if I provide her proper dimension and I am looking into how to make one. I know Gunwan has some theory and drawing on his website at
http://gwidijanto.fcpages.com/reflector.htm
I also found this interesting info on elliptical reflector at:
http://www.phys.ncku.edu.tw/optics/technical/commerical/tracepro/Tutorials/Metal Halide Tutorial.pdf
After spending several hours to read the forum I have concluded the following:
1. Point source light (Fluorex are not suitable even if you have two of them - other people have tried them with not so impressive results)
2. Ellipsoidal reflector to focus all the light and redistribute evenlly on the panel
3. MH 250W+ is the start point higher W is better if heat issues can be resolved (Low E glass barrier, Fans, etc.)
4. Line doubler or similar device helps (I have tv 4000 and my test results shows excellent sharp image at 800 X 600 resolution (Nview z255 panel). Also, TV 4000 has a remote which helps to change brighness/contrast etc while watching movies. I show pre-recorded Alias from my VCR yesterday on 6 X 6 Da Lite screen last night (with lights off in living room) and after adjusting brightness etc.. My wife and I were very happy with the image quality. Than we played a DVD in wide screen format and it was awsome.
5. Based on the room dimension, OHP optic may not be suitable. I had to put my OHP at about 10 feet to get the image to fit on my 6 X 6 screen. I need atleast a 15 feet throw distance to get the similar size projection so am looking for some lenses.
What bulb/reflector you are looking into? 16 X 8 reflector sound a little big but still manageable. Is it ellipsoidal or parabolic? I have a friend who is into glass blowing and I talked to her yesterday she can make a reflector from glass if I provide her proper dimension and I am looking into how to make one. I know Gunwan has some theory and drawing on his website at
http://gwidijanto.fcpages.com/reflector.htm
I also found this interesting info on elliptical reflector at:
http://www.phys.ncku.edu.tw/optics/technical/commerical/tracepro/Tutorials/Metal Halide Tutorial.pdf
Yes, I reached pretty much the same conclusions. However, I think that the reason uvodee is having success with his fluorex lights where no one else has is that he _doesn't_ try and treat the light as a point-source that needs to be focused into a beam. He has chosen instead to just let the light pass thru the apeture as it is. As such, he is probably not getting as efficient use of the light as possible, but it obviously works for him.
I think that there is going to be a fundamental problem with the use of "standard" MH bulbs: the internal elements of the bulb get in the way of creating a clean, precise beam.
<img src="http://members.cox.net/rolm/images/mh_bulb00.jpg">
This uneven placement of the point source of the light makes it difficult to use a standard conical reflector (either parabolic or ellipsoidal) to get a clean, even beam.
<img src="http://members.cox.net/rolm/images/mh_bulb01.jpg">
The MH- driven OHPs use a double-ended MH bulb to get around this. Double-ended means that they can precisely place the point-source because there is none of the U-turn nonsense in the element. The downside is that the high-wattage double-ended bulb is very expensive.
Another idea is to create a rectangular or tubular reflector and mount the bulb on it's side instead of head-on:
<img src="http://members.cox.net/rolm/images/floodzilla.gif">
This makes it much easier to place the point-source at the center of the reflector. It is possible to also add angled reflectors on either side of the bulb to scavenge even more light.
I, being the cheap bastard that I am (and having blown about ~$150 on a failed attempt to use a MH PAR bulb) am now trying to do something like the rectangular setup:
<a href="http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=3186&item=2077089289">
<img src="http://abacus.sj.ipixmedia.com/abc/M28/_EBAY_27e84836ec902925a92c4b45d5/i-1.JPG">
400w light from ebay
</a>
The reflector is not ellipsoidal, but it's a start, and it's a bulb, socket, ballast and metal reflector for $100. This is kind of taking a page from uvodee and trying to make as much light as possible available, and hoping that enough of it goes in the right direction. If I get promising results from this, then I'll begin trying to make a decent ellipsoidal rectangular reflector.
I guess I'm opting for the bigger hammer here, rather than the more refined technique of trying to make a custom glass reflector (which would be awesome if you could pull it off). I'm just concerned that you might sink an awful lot of time and effort into making said reflector, only to be unable to locate a bulb that will allow you to truly center the point-source of the light.
I'm also trying to divide and conquer: rather than trying to create a good, bright light source AND come up with a good optics system, I'm re-using the optics from the existing OHP and just trying to solve the light problem. If I solve the light problem, then I'll consider rearranging the optics of the projector.
Your TV-4000 sounds a LOT better than what I have. I just bought the $80 cheese-box, mainly because (at the time) the OHP that I had was only capable of 640x480. However, it sounds like I should have bought what you bought. Oh well, nothing a little more money won't fix... just wish I had some...
I think that there is going to be a fundamental problem with the use of "standard" MH bulbs: the internal elements of the bulb get in the way of creating a clean, precise beam.
<img src="http://members.cox.net/rolm/images/mh_bulb00.jpg">
This uneven placement of the point source of the light makes it difficult to use a standard conical reflector (either parabolic or ellipsoidal) to get a clean, even beam.
<img src="http://members.cox.net/rolm/images/mh_bulb01.jpg">
The MH- driven OHPs use a double-ended MH bulb to get around this. Double-ended means that they can precisely place the point-source because there is none of the U-turn nonsense in the element. The downside is that the high-wattage double-ended bulb is very expensive.
Another idea is to create a rectangular or tubular reflector and mount the bulb on it's side instead of head-on:
<img src="http://members.cox.net/rolm/images/floodzilla.gif">
This makes it much easier to place the point-source at the center of the reflector. It is possible to also add angled reflectors on either side of the bulb to scavenge even more light.
I, being the cheap bastard that I am (and having blown about ~$150 on a failed attempt to use a MH PAR bulb) am now trying to do something like the rectangular setup:
<a href="http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=3186&item=2077089289">
<img src="http://abacus.sj.ipixmedia.com/abc/M28/_EBAY_27e84836ec902925a92c4b45d5/i-1.JPG">
400w light from ebay
</a>
The reflector is not ellipsoidal, but it's a start, and it's a bulb, socket, ballast and metal reflector for $100. This is kind of taking a page from uvodee and trying to make as much light as possible available, and hoping that enough of it goes in the right direction. If I get promising results from this, then I'll begin trying to make a decent ellipsoidal rectangular reflector.
I guess I'm opting for the bigger hammer here, rather than the more refined technique of trying to make a custom glass reflector (which would be awesome if you could pull it off). I'm just concerned that you might sink an awful lot of time and effort into making said reflector, only to be unable to locate a bulb that will allow you to truly center the point-source of the light.
I'm also trying to divide and conquer: rather than trying to create a good, bright light source AND come up with a good optics system, I'm re-using the optics from the existing OHP and just trying to solve the light problem. If I solve the light problem, then I'll consider rearranging the optics of the projector.
Your TV-4000 sounds a LOT better than what I have. I just bought the $80 cheese-box, mainly because (at the time) the OHP that I had was only capable of 640x480. However, it sounds like I should have bought what you bought. Oh well, nothing a little more money won't fix... just wish I had some...
good deal
thats pretty cheap price for the bulb, ballast, and reflector set up.. I remember seeing on ebay before and he has several of them which is good.
Uvodee has used two fluorex lamps but If I remember correctly his panel is 5' so it works well...I think for large panels we might get dark corners.
I talked to my friend again about making the reflector and he said it would be easy to make it in ceramic than glass if I provide him with the measurements..They make several style bowls in ceramic and they are very cheap (<$10 each). Now the question is how to make the inner surface reflective... I am looking for tiny mirrors from craft stores and planning on sticking them inside the ceramic reflector. The other idea is to paint the surface with some sort of metalic reflective paint.. I am not sure how the heat is going to affect mirrors/paint though.
The offcenter set up of MH should not be a problem since I can mount the lamp a little bit off center so that the lighting element falls in the center of the reflector.
If I decide to use the home made reflector than I will be looking for tubular metal halide than the round one so it fits well in the reflector.
thats pretty cheap price for the bulb, ballast, and reflector set up.. I remember seeing on ebay before and he has several of them which is good.
Uvodee has used two fluorex lamps but If I remember correctly his panel is 5' so it works well...I think for large panels we might get dark corners.
I talked to my friend again about making the reflector and he said it would be easy to make it in ceramic than glass if I provide him with the measurements..They make several style bowls in ceramic and they are very cheap (<$10 each). Now the question is how to make the inner surface reflective... I am looking for tiny mirrors from craft stores and planning on sticking them inside the ceramic reflector. The other idea is to paint the surface with some sort of metalic reflective paint.. I am not sure how the heat is going to affect mirrors/paint though.
The offcenter set up of MH should not be a problem since I can mount the lamp a little bit off center so that the lighting element falls in the center of the reflector.
If I decide to use the home made reflector than I will be looking for tubular metal halide than the round one so it fits well in the reflector.
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