Well I had a bright idea..I tried it...just hand holding the gear. But the results look very promising. Other than the fact I dont know for a fact where F2 is... Optics will be my struggle in this project I think. Not my strong suit...so I guess I gotta crack a couple of books .
zardoz
zardoz
the reflector is not Paraboloid Ellipsoid or Cone
the reflector
using spherical reflector to reflect back the light to the lamp, not Paraboloid Ellipsoid or Cone
this is my friend's:
http://photos.gznet.com/photos/1013684/1013684-gMlbjRoQMJQe2qazsk!RZmrALtw6kK.JPG
http://photos.gznet.com/photos/1013684/1013684-6HadMFdv5KrelFZ7nApznadrM1FczI.JPG
the reflector
using spherical reflector to reflect back the light to the lamp, not Paraboloid Ellipsoid or Cone
this is my friend's:
http://photos.gznet.com/photos/1013684/1013684-gMlbjRoQMJQe2qazsk!RZmrALtw6kK.JPG
http://photos.gznet.com/photos/1013684/1013684-6HadMFdv5KrelFZ7nApznadrM1FczI.JPG
reflectors
ywh:
The second link with a picture of double ended bulb with a reflector at the bottom is what I have in my EIKI overhead projector and it looks like "parabolic". I think it works pretty well with the halogen bulb I have in overhead projector. As soon as I get my metal halide lamp - I have posted picture earlier in this thread (150W cap style single ended made by GE) - I will try using that with the OHP reflector (parabolic shape). The dimensions seems to be pretty much similar and I dont think of any reason why it should not work.
By the way, I liked your posting and results. Keep on sharing the info and outcome on various aspects. I am glad you can find things in local market. And dont worry about your English! I lived in China (Shanghai - East China Normal University) as an exchange student for a year and liked travelling around. Most of my vacation time was spent in YenCheng (wetland - marshland) watching Migratory birds.
ywh:
The second link with a picture of double ended bulb with a reflector at the bottom is what I have in my EIKI overhead projector and it looks like "parabolic". I think it works pretty well with the halogen bulb I have in overhead projector. As soon as I get my metal halide lamp - I have posted picture earlier in this thread (150W cap style single ended made by GE) - I will try using that with the OHP reflector (parabolic shape). The dimensions seems to be pretty much similar and I dont think of any reason why it should not work.
By the way, I liked your posting and results. Keep on sharing the info and outcome on various aspects. I am glad you can find things in local market. And dont worry about your English! I lived in China (Shanghai - East China Normal University) as an exchange student for a year and liked travelling around. Most of my vacation time was spent in YenCheng (wetland - marshland) watching Migratory birds.
ywh -
Yes, that little reflector back there could be spherical. The advantage there is that the diameter of the reflector is quite small. If I'm not mistaken, that's an "atmospheric" or "condenser" lens that is placed in front of it, for the purposes of spreading out the beam.
For that setup, a spherical reflector works quite well, because you have a very small light source (HQI bulb): approximately 1/2" (~12mm) in diameter. We are dealing with bulbs that are 4-1/2" (~115mm) in diameter, so we end up needing very large reflectors. If the size of a spherical reflector exceeds the diagonal measurement of the LCD, then we're wasting light, since a spherical reflector throws a parallel beam.
Another difference btw your example and what we've been talking about is that what you're showing is an "open" element setup, and we've been discussing "closed" elements, where the reflector encloses the bulb on all sides but one.
That being said, I've seen the pictures of your setup, and I'm jealous: I hope I can get results half as good as yours.
Yes, that little reflector back there could be spherical. The advantage there is that the diameter of the reflector is quite small. If I'm not mistaken, that's an "atmospheric" or "condenser" lens that is placed in front of it, for the purposes of spreading out the beam.
For that setup, a spherical reflector works quite well, because you have a very small light source (HQI bulb): approximately 1/2" (~12mm) in diameter. We are dealing with bulbs that are 4-1/2" (~115mm) in diameter, so we end up needing very large reflectors. If the size of a spherical reflector exceeds the diagonal measurement of the LCD, then we're wasting light, since a spherical reflector throws a parallel beam.
Another difference btw your example and what we've been talking about is that what you're showing is an "open" element setup, and we've been discussing "closed" elements, where the reflector encloses the bulb on all sides but one.
That being said, I've seen the pictures of your setup, and I'm jealous: I hope I can get results half as good as yours.
Reflector ideas
zardoz:
As rolm said, only elliptical reflector is designed for an end cap with a small apparture. The function of an elliptical reflector is to "collect" light for a point source lamp (F1) and point it to another focal point (F2) where its even and can be redirected to the LCD panel to illuminate the panel evenly. If you read this thread we have pretty good discussion on how this thing works.
I have put a great deal of time reading and thinking about various ways to work with light in the projector set up and IMHO elliptical reflector is probably the best way to avoide potential hotspot and use all the light from the lamp efficiently.
The reflector I have is made for theater lights and landscape lights using metal halide lamps up to 400 W. To find out F1 and F2 in a true or reasonably elliptical reflector should not be an issue. I have done it using an LED light but you can also use meglight with the top reflector part off - jsut the bulb on top and try sliding it back and forth in the reflector from the bottom and observe the beam behavior.
zardoz:
As rolm said, only elliptical reflector is designed for an end cap with a small apparture. The function of an elliptical reflector is to "collect" light for a point source lamp (F1) and point it to another focal point (F2) where its even and can be redirected to the LCD panel to illuminate the panel evenly. If you read this thread we have pretty good discussion on how this thing works.
I have put a great deal of time reading and thinking about various ways to work with light in the projector set up and IMHO elliptical reflector is probably the best way to avoide potential hotspot and use all the light from the lamp efficiently.
The reflector I have is made for theater lights and landscape lights using metal halide lamps up to 400 W. To find out F1 and F2 in a true or reasonably elliptical reflector should not be an issue. I have done it using an LED light but you can also use meglight with the top reflector part off - jsut the bulb on top and try sliding it back and forth in the reflector from the bottom and observe the beam behavior.
yet another reflector..
I finally got my hands on a true "eliptical" reflector. Huge differance! Looks like I totalled 2 perfectly good SST bowls for nothing 😱
Oh well all in the spirit of DIY. This one is alluminum but is painted white, do you think I should chemically strip the paint and pollish it? I'm sure I can get it VERY shiny. It's a prety big reflector, but I can deal with that.
zardoz
I finally got my hands on a true "eliptical" reflector. Huge differance! Looks like I totalled 2 perfectly good SST bowls for nothing 😱
Oh well all in the spirit of DIY. This one is alluminum but is painted white, do you think I should chemically strip the paint and pollish it? I'm sure I can get it VERY shiny. It's a prety big reflector, but I can deal with that.
zardoz
You could strip & paint, or you could get some reflective mylar film and glue it to the inside. That should give you an easy mirror finish, as long as you get it nice and flat.
So where'd you get the elliptical reflector?
So where'd you get the elliptical reflector?
Rolm
I got this one from the local building wrecker, it had a 250 watt ballast attached to it. $75.00. I asked if I could buy just the reflector..offered the guy 30 bucks for it..he sold it to me for 25 plus a couple of Sylvania bulbs..total bill 32 bucks and change. I think I like the Sylvania's much better than the GE's I've been experimenting with. The quallity of light seems superior.
zardoz
I got this one from the local building wrecker, it had a 250 watt ballast attached to it. $75.00. I asked if I could buy just the reflector..offered the guy 30 bucks for it..he sold it to me for 25 plus a couple of Sylvania bulbs..total bill 32 bucks and change. I think I like the Sylvania's much better than the GE's I've been experimenting with. The quallity of light seems superior.
zardoz
Yeah, the first GE I got was chipped, which I didn't notice until it blew up. I'm now using a Philips, which some ppl don't like, but I've had no complaints.
A building wrecker, eh? I may have to see if I can find one around here...
A building wrecker, eh? I may have to see if I can find one around here...
Re: reflectors
rajkumar:
welcome to YenCheng again! I live in YenCheng ( guangzhou )
you will to see anything at my overhead projector ,you well to get anything.double ended bulb ,reflector.
"The dimensions seems to be pretty much similar and I dont think of any reason why it should not work."
I don't know what are you talking about
The firster link is
rajkumar:
welcome to YenCheng again! I live in YenCheng ( guangzhou )
you will to see anything at my overhead projector ,you well to get anything.double ended bulb ,reflector.
"The dimensions seems to be pretty much similar and I dont think of any reason why it should not work."
I don't know what are you talking about
The firster link is
An externally hosted image should be here but it was not working when we last tested it.
Rolm
why you didnn't deal with bulbs that are (~12mm) in diameter?
HQI bulb is made in osram,like this :
http://photos.gznet.com/photos/1013684/1013684-5CIqI$PG5ilv194fZsCLICV11SsbBI.JPG
http://photos.gznet.com/photos/1013684/1013684-zfNJwm7s7k7eqho2NQzj61$ZNRH7bG.JPG
This is 250w osram:http://photos.gznet.com/photos/1013684/1013684-gMlbjRoQMJQe2qazsk!RZmrALtw6kK.JPG
my firend using it :
http://photos.gznet.com/photos/1013684/1013684-1g6s5jKEHnAh5wc9fiw$$wjvEaFP2m.jpg
http://photos.gznet.com/photos/1013684/1013684-m$hSAv7V!pkm7nvEz1IqQlfmlgdA8Q.jpg
He got a 3M 1720 PROJECTOR ,and change the lamp.
http://photos.gznet.com/photos/1013684/1013684-kPsZEIdI5SFRjthqRGIRkJcK53sZkb.JPG
http://photos.gznet.com/photos/1013684/1013684-PkiOO76JqQ97jIP5lkfhw9zaEr7EVj.JPG
why you didnn't deal with bulbs that are (~12mm) in diameter?
HQI bulb is made in osram,like this :
http://photos.gznet.com/photos/1013684/1013684-5CIqI$PG5ilv194fZsCLICV11SsbBI.JPG
http://photos.gznet.com/photos/1013684/1013684-zfNJwm7s7k7eqho2NQzj61$ZNRH7bG.JPG
This is 250w osram:http://photos.gznet.com/photos/1013684/1013684-gMlbjRoQMJQe2qazsk!RZmrALtw6kK.JPG
my firend using it :
http://photos.gznet.com/photos/1013684/1013684-1g6s5jKEHnAh5wc9fiw$$wjvEaFP2m.jpg
http://photos.gznet.com/photos/1013684/1013684-m$hSAv7V!pkm7nvEz1IqQlfmlgdA8Q.jpg
An externally hosted image should be here but it was not working when we last tested it.
He got a 3M 1720 PROJECTOR ,and change the lamp.
http://photos.gznet.com/photos/1013684/1013684-kPsZEIdI5SFRjthqRGIRkJcK53sZkb.JPG
http://photos.gznet.com/photos/1013684/1013684-PkiOO76JqQ97jIP5lkfhw9zaEr7EVj.JPG
ywh,
I decided not to deal with the HQI bulbs for 2 reasons:
(1) price. My bulb is about $20, whereas a comparable (400w) HQI is rare; the only one I found was ~$250.
(2) precision. If I deal with a larger bulb, I don't have to be as precise with making the reflector. You and your friend have the advantage of working with a premade system, whereas I am making everything myself.
Reason (2) is probably why you get such excellent results with a lower wattage bulb. You have a premanufactured bulb holder/reflector/lens that is very precisely made. There is little chance that I'm going to be able to make a precise 2" (50mm) spherical reflector in my home workshop. However, I have been able to make a 12"x14" (30cm X 35cm) rectangular reflector that can focus the light into a 1/2" (12mm) band.
As noted, I have since abandoned the concept of a "rectangular" reflector because it simply doesn't reflect enough of the available light. However, I am still going to try to find a way to use the $20 bulb.
I have a question, perhaps I have missed the answer in some of your other postings: I looked up "3M 1720", and according to all info it uses an ENX bulb. So where did you come up with the HQI bulb holder/reflector/lens setup? I would be VERY interested to find this out...
I decided not to deal with the HQI bulbs for 2 reasons:
(1) price. My bulb is about $20, whereas a comparable (400w) HQI is rare; the only one I found was ~$250.
(2) precision. If I deal with a larger bulb, I don't have to be as precise with making the reflector. You and your friend have the advantage of working with a premade system, whereas I am making everything myself.
Reason (2) is probably why you get such excellent results with a lower wattage bulb. You have a premanufactured bulb holder/reflector/lens that is very precisely made. There is little chance that I'm going to be able to make a precise 2" (50mm) spherical reflector in my home workshop. However, I have been able to make a 12"x14" (30cm X 35cm) rectangular reflector that can focus the light into a 1/2" (12mm) band.
As noted, I have since abandoned the concept of a "rectangular" reflector because it simply doesn't reflect enough of the available light. However, I am still going to try to find a way to use the $20 bulb.
I have a question, perhaps I have missed the answer in some of your other postings: I looked up "3M 1720", and according to all info it uses an ENX bulb. So where did you come up with the HQI bulb holder/reflector/lens setup? I would be VERY interested to find this out...
spider reflector?
this looks helpful.. http://www.hellolights.com/methalparref.html
this looks helpful.. http://www.hellolights.com/methalparref.html
An externally hosted image should be here but it was not working when we last tested it.
Rolm
once again for that picture
HQI bulb is made in osram,like this :
![url]$ZNRH7bG.JPG](/community/proxy.php?image=http%3A%2F%2F%5Burl%5Dhttp%3A%2F%2Fphotos.gznet.com%2Fphotos%2F1013...s7k7eqho2NQzj61%5B%2Furl%5D%24ZNRH7bG.JPG&hash=a18a6b28c90e20e2486a9ce7acdaa093)
This is 250w osram,you can get it everywhere.
[url]http://photos.gznet.com/photos/1013...bjRoQMJQe2qazsk[/url]!RZmrALtw6kK.JPG
my firend using it 😱sram,240w,US$:40,very longer live,more than 10000H,it is evry cheap,and the 3M 1720 PROJECTOR ,US$:200
You 're going to be able to make a precise 2" (50mm) spherical reflector in your home workshop. but the reflector will to be rust in heat light
once again for that picture
HQI bulb is made in osram,like this :
An externally hosted image should be here but it was not working when we last tested it.
This is 250w osram,you can get it everywhere.
[url]http://photos.gznet.com/photos/1013...bjRoQMJQe2qazsk[/url]!RZmrALtw6kK.JPG
my firend using it 😱sram,240w,US$:40,very longer live,more than 10000H,it is evry cheap,and the 3M 1720 PROJECTOR ,US$:200
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
You 're going to be able to make a precise 2" (50mm) spherical reflector in your home workshop. but the reflector will to be rust in heat light
ywh,
Ok, my research shows that the 3M 1720 uses an ENX bulb like this:
<img src="http://64.95.118.51/images/opti/d1/09/dfe350ca9976b6606d64ea91e64e659c1-resized200.jpg"</img>
But you are using this assembly to replace the ENX assembly:
<img src="http://photos.gznet.com/photos/1013684/1013684-gMlbjRoQMJQe2qazsk!RZmrALtw6kK.JPG"</img>
Where did you get this <b>entire assembly</b>? Not just the bulb, but the <b>whole thing</b>: lamp holder, bracketry, reflector, lens, the entire assembly? Is this the assembly that came with the 3m 1720, and if so did you just add the HQI lamp holder and make a reflector? If so, how did you make the reflector?
The reason I seem so confused is that this assembly appears to be very different from the standard ENX bulb holder, and therefore the <b>entire assembly</b> would be required to replace and ENX lamp with your 150/250W HQI bulbs.
I currently have a 3M OHP that uses the ENX bulb, and my bulb assembly doesn't look anything like this; mine is about 1/4 the size of that one, and doesn't use any lenses at all.
Ok, my research shows that the 3M 1720 uses an ENX bulb like this:
<img src="http://64.95.118.51/images/opti/d1/09/dfe350ca9976b6606d64ea91e64e659c1-resized200.jpg"</img>
But you are using this assembly to replace the ENX assembly:
<img src="http://photos.gznet.com/photos/1013684/1013684-gMlbjRoQMJQe2qazsk!RZmrALtw6kK.JPG"</img>
Where did you get this <b>entire assembly</b>? Not just the bulb, but the <b>whole thing</b>: lamp holder, bracketry, reflector, lens, the entire assembly? Is this the assembly that came with the 3m 1720, and if so did you just add the HQI lamp holder and make a reflector? If so, how did you make the reflector?
The reason I seem so confused is that this assembly appears to be very different from the standard ENX bulb holder, and therefore the <b>entire assembly</b> would be required to replace and ENX lamp with your 150/250W HQI bulbs.
I currently have a 3M OHP that uses the ENX bulb, and my bulb assembly doesn't look anything like this; mine is about 1/4 the size of that one, and doesn't use any lenses at all.
3M 1720 uses an ENX bulb like that but has not reflector
My friend get thiat entire assembly at 3M,He give it a new bulb, a lamp holder,the bracketry, reflector, lens came with the 3m 1720, he buy the new bulb, the new lamp holder ,only,
My friend get thiat entire assembly at 3M,He give it a new bulb, a lamp holder,the bracketry, reflector, lens came with the 3m 1720, he buy the new bulb, the new lamp holder ,only,
OK, I hope my understanding of you is correct:
All that your friend added to the 3M 1720 was a bulb-holder, the bulb, and the reflector. Other than that, the entire assembly pictured was already in the 1720.
In other words, if I wanted to do the same thing, all I would need is:
(1) 3M 1720
<img src="http://www.unitedvisual.com/jpeg/MM1720.jpg">
(2) an HQI bulb
<a href="http://store.yahoo.com/lamps-now/1510hqidoube.html">
<img width=250 src="http://store2.yimg.com/I/lamps-now_1717_1043712">
</a>
(3) HQI bulb holder
<a href="http://www.hellolights.com/25lamholwitb1.html">
<img width =250 src="http://store2.yimg.com/I/lamps-now_1719_94164">
</a>
(4) home-made ~2" reflector like this:
<img src="http://catalog.sciencekit.com/ProductImageLib/30/30538-75g.eps.jpg">
I would <b>NOT</b> have to buy any parts from some other OHP to make it work, right?
If you can verify this, then I will probably start buying some of these things. I just managed to mangle some of the parts I took from my other OHP, so I'm looking to buy anyways.
All that your friend added to the 3M 1720 was a bulb-holder, the bulb, and the reflector. Other than that, the entire assembly pictured was already in the 1720.
In other words, if I wanted to do the same thing, all I would need is:
(1) 3M 1720
<img src="http://www.unitedvisual.com/jpeg/MM1720.jpg">
(2) an HQI bulb
<a href="http://store.yahoo.com/lamps-now/1510hqidoube.html">
<img width=250 src="http://store2.yimg.com/I/lamps-now_1717_1043712">
</a>
(3) HQI bulb holder
<a href="http://www.hellolights.com/25lamholwitb1.html">
<img width =250 src="http://store2.yimg.com/I/lamps-now_1719_94164">
</a>
(4) home-made ~2" reflector like this:
<img src="http://catalog.sciencekit.com/ProductImageLib/30/30538-75g.eps.jpg">
I would <b>NOT</b> have to buy any parts from some other OHP to make it work, right?
If you can verify this, then I will probably start buying some of these things. I just managed to mangle some of the parts I took from my other OHP, so I'm looking to buy anyways.
no !
3m 1720:the bracketry, reflector, lens came
My friend bought the new bulb, the new lamp holder,
your 3m 1720 is not Chinese 3m 1720 !why ?Chinese 3m 1720 is:
http://www.3m.com/intl/cn/office/demo/gaoshe/product_m1720.html
250W HQI bulbs is right for 100" screen.
if 150W £¬dont more than 70"screen,My friend using 250W HQI bulbs
but ,250W is very expensive at HELLOLIGHTS.US$:40 in China
3m 1720:the bracketry, reflector, lens came
My friend bought the new bulb, the new lamp holder,
your 3m 1720 is not Chinese 3m 1720 !why ?Chinese 3m 1720 is:
http://www.3m.com/intl/cn/office/demo/gaoshe/product_m1720.html
An externally hosted image should be here but it was not working when we last tested it.
250W HQI bulbs is right for 100" screen.
if 150W £¬dont more than 70"screen,My friend using 250W HQI bulbs
but ,250W is very expensive at HELLOLIGHTS.US$:40 in China
Hm, I suspect you are right, and the Chinese version of the 1720 is different than the western one.
I suspect that your friend's 1720 originally used an EHJ bulb. Am I correct?
OHPs that use the EHJ-type bulbs are probably the ones that are capable of being easily upgraded to a Xenon or MH HQI bulb, because (I am pretty sure) that they all use the apparatus pictured earlier in this thread, with the seperate reflector and lens.
As noted, the western version of the 1720 uses an ENX/FXL style bulb, and therefore has no lens and the reflector is built into the bulb. If an OHP uses an ENX/FXL-style bulb, it is definitely NOT a candidate for this modification, or at least not as easily.
In any event, I've trashed my OHP at this point (I broke the thermal glass that is bonded to the fresnel), so I'm in the market for another OHP. I will try to buy one that uses an EHJ bulb. If, as I hope, that means that it comes with this apparatus, I will try to do the same mod you have done.
Thank you, ywh, for your patience in answering my questions.
I suspect that your friend's 1720 originally used an EHJ bulb. Am I correct?
OHPs that use the EHJ-type bulbs are probably the ones that are capable of being easily upgraded to a Xenon or MH HQI bulb, because (I am pretty sure) that they all use the apparatus pictured earlier in this thread, with the seperate reflector and lens.
As noted, the western version of the 1720 uses an ENX/FXL style bulb, and therefore has no lens and the reflector is built into the bulb. If an OHP uses an ENX/FXL-style bulb, it is definitely NOT a candidate for this modification, or at least not as easily.
In any event, I've trashed my OHP at this point (I broke the thermal glass that is bonded to the fresnel), so I'm in the market for another OHP. I will try to buy one that uses an EHJ bulb. If, as I hope, that means that it comes with this apparatus, I will try to do the same mod you have done.
Thank you, ywh, for your patience in answering my questions.
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