Its HUGE!
Sorry to hear about UPS thing. Seems like the whole set up is HUGE.. I think you gonna have to make a custome box for the projector it will not fit in the standard IKEA box that several people are using to build the projector unless you replace the reflector..
I have placed two orders, one for 150W Metal halide set up (bulb 4 inch long Tubular, less than 1 inch diameter 12K lumen with electronic ballast) and the other 400 W set up (5 inch long bulb). After placing order for the 150W bulb, I have been looking for the GY 12 base (BiPin ceramic base for the bulb) and have not been able to find one..its not readily available online..see what happens.
I did get a response for my original 150W GE bulb (tiny bulb <2 inch long and <1 inch diameter) from one online retailer so I am going to order that as well since I can use my 150 ballast for that. If I will get the GE bulb that I would be able to retrofit my OHP.
While waiting for the bulb set up I am working on the screen and a long throw projector lens to fit in my living room set up.
Sorry to hear about UPS thing. Seems like the whole set up is HUGE.. I think you gonna have to make a custome box for the projector it will not fit in the standard IKEA box that several people are using to build the projector unless you replace the reflector..
I have placed two orders, one for 150W Metal halide set up (bulb 4 inch long Tubular, less than 1 inch diameter 12K lumen with electronic ballast) and the other 400 W set up (5 inch long bulb). After placing order for the 150W bulb, I have been looking for the GY 12 base (BiPin ceramic base for the bulb) and have not been able to find one..its not readily available online..see what happens.
I did get a response for my original 150W GE bulb (tiny bulb <2 inch long and <1 inch diameter) from one online retailer so I am going to order that as well since I can use my 150 ballast for that. If I will get the GE bulb that I would be able to retrofit my OHP.
While waiting for the bulb set up I am working on the screen and a long throw projector lens to fit in my living room set up.
Yes, it's gigantic. On the upside, it looks like it might be a half-decent fit for the back of the OHP. I dunno, I have to fiddle with it, and will probably make a mating panel.
It's a shame that the smaller (physically) bulbs are so expensive. I was thinking that a multiple-bulb setup might work pretty well for small bulbs. And since 2 x 150w = 300w, that would play nicely to what we're trying to do.
As it is, I'll be happy if I can get this big honkin bulb working. I'm not bothering with trying to file a claim with UPS, I'm just going to go buy another bulb (they're only about $20). Impatience gets the better of me...
It's a shame that the smaller (physically) bulbs are so expensive. I was thinking that a multiple-bulb setup might work pretty well for small bulbs. And since 2 x 150w = 300w, that would play nicely to what we're trying to do.
As it is, I'll be happy if I can get this big honkin bulb working. I'm not bothering with trying to file a claim with UPS, I'm just going to go buy another bulb (they're only about $20). Impatience gets the better of me...
small bulb set up
I have been thinking about the two lamp set up using two small 150 W lamps (100 hrs life, 12K lumens, $63 each) and finally found a retailer online right in my own city (san francisco!). I ordered two of them with GY 9.5 bases ($12 each). They do have base on stock so I will pick it up tomorrow and the bulbs will be available in a week or so. The measurements for the bulb is 1.62 inch long, 3/4 diameter and the light center length is 1.2 inch which is almost identical to the Halogen lamp I have in EIKI OHP with a separate reflector at the bottom. I wish I would have known this before since I already ordered a 150W metal halide electronic ballast and its shipped. I later found out that I could have bought magnetic dual ballast that can run two of this lamps and the cost is same as single electronic ballast.. oh well. will buy the dual as well.
Since the bulbs are really tiny, I am thinking of putting two of them side by side with two reflectors and see how that will work out. I only have one reflector from EIKI OHP and am looking for another reflector.. it looks pretty much like a small half round 3.5 inch bowl.. may me a small stainless steel bowl of that size can do the trick.. Will post some pictures later showing the EIKI setup.
I also ordered a PAR reflector from partsexpress with GY 9.5 base and waiting to see how it works.
I have been thinking about the two lamp set up using two small 150 W lamps (100 hrs life, 12K lumens, $63 each) and finally found a retailer online right in my own city (san francisco!). I ordered two of them with GY 9.5 bases ($12 each). They do have base on stock so I will pick it up tomorrow and the bulbs will be available in a week or so. The measurements for the bulb is 1.62 inch long, 3/4 diameter and the light center length is 1.2 inch which is almost identical to the Halogen lamp I have in EIKI OHP with a separate reflector at the bottom. I wish I would have known this before since I already ordered a 150W metal halide electronic ballast and its shipped. I later found out that I could have bought magnetic dual ballast that can run two of this lamps and the cost is same as single electronic ballast.. oh well. will buy the dual as well.
Since the bulbs are really tiny, I am thinking of putting two of them side by side with two reflectors and see how that will work out. I only have one reflector from EIKI OHP and am looking for another reflector.. it looks pretty much like a small half round 3.5 inch bowl.. may me a small stainless steel bowl of that size can do the trick.. Will post some pictures later showing the EIKI setup.
I also ordered a PAR reflector from partsexpress with GY 9.5 base and waiting to see how it works.
Sigh...
Okay, it looks like I'm going to have to abandon my idea of not messing with the basic OHP. The bulb is too large to allow itself to be placed where I need it to be, and that enormous reflector is not properly shaped to give me the clear light that I need.
I was able to essentially re-make the OHP by making a new stage to mount the fresnel in and suspending it above the enormous reflector. The problem is that the reflector is decidedly not elliptical (ie the beam just gets wider after the reflector) and it's already wider than the fresnel (let alone the LCD), so I'm wasting probably more than half my light even if I put the stage right on top of the reflector.
The answer is unfortuately a step backwards: make my own reflector. With the size of this bulb (11" long and 4-1/2" diam), it's going to have to be elliptical and rectangular.
I'm going to use the pencil-and-string method from the page you linked to make a reflector that will probably be 1.5X to 2X the height of the LCD (since the LCD is only about 6" high). I plan on only making the one dimension at first (ie like a half-pipe). If I end up with a distorted beam then I'll make the second.
There are images of my tests, but I'll probably wait to post them (since they're only images of unsuccessful tests 🙁 ) until later. Or I'll make a webpage-o-shame of my mistakes.
Okay, it looks like I'm going to have to abandon my idea of not messing with the basic OHP. The bulb is too large to allow itself to be placed where I need it to be, and that enormous reflector is not properly shaped to give me the clear light that I need.
I was able to essentially re-make the OHP by making a new stage to mount the fresnel in and suspending it above the enormous reflector. The problem is that the reflector is decidedly not elliptical (ie the beam just gets wider after the reflector) and it's already wider than the fresnel (let alone the LCD), so I'm wasting probably more than half my light even if I put the stage right on top of the reflector.
The answer is unfortuately a step backwards: make my own reflector. With the size of this bulb (11" long and 4-1/2" diam), it's going to have to be elliptical and rectangular.
I'm going to use the pencil-and-string method from the page you linked to make a reflector that will probably be 1.5X to 2X the height of the LCD (since the LCD is only about 6" high). I plan on only making the one dimension at first (ie like a half-pipe). If I end up with a distorted beam then I'll make the second.
There are images of my tests, but I'll probably wait to post them (since they're only images of unsuccessful tests 🙁 ) until later. Or I'll make a webpage-o-shame of my mistakes.
Fog lights with elliptical reflector
Rolm,
Retrofitting OHP is viable only if you have small lamp/reflector set up. I got my ballast (150/175 W electronic from hallolight) a few days ago, picked up GY 9.5 and G 12 sockets from Buhl Distributors in SF yesterday, PAR 56, 64 reflectors are in the mail and so as two 150W lamps. I am going to IKEA tomorrow to pick up APS toy chest for $9.99 and will start building the box. I am working on both (OHP retro and Custom Box) approaches side by side.
While searching for the reflectors, I found out that elliptical reflectors are used in car fog lights - I am not sure if they are plastic, glass or metal but I am looking for them. Example and links enclosed.
Auto Fog lights with elliptical reflectors:
http://www.jcwhitneyusa.com/catsubpic.jhtml;$sessionid$CO5EXEAAAABD2QSNDV1CFFCCJUOXKIV0?CATID=3219&BQ=jcw2
Custom box for MH 400 with reflector:
http://users.erols.com/martinm/gaffs/diyprojector.htm
Rolm,
Retrofitting OHP is viable only if you have small lamp/reflector set up. I got my ballast (150/175 W electronic from hallolight) a few days ago, picked up GY 9.5 and G 12 sockets from Buhl Distributors in SF yesterday, PAR 56, 64 reflectors are in the mail and so as two 150W lamps. I am going to IKEA tomorrow to pick up APS toy chest for $9.99 and will start building the box. I am working on both (OHP retro and Custom Box) approaches side by side.
While searching for the reflectors, I found out that elliptical reflectors are used in car fog lights - I am not sure if they are plastic, glass or metal but I am looking for them. Example and links enclosed.
Auto Fog lights with elliptical reflectors:
http://www.jcwhitneyusa.com/catsubpic.jhtml;$sessionid$CO5EXEAAAABD2QSNDV1CFFCCJUOXKIV0?CATID=3219&BQ=jcw2
Custom box for MH 400 with reflector:
http://users.erols.com/martinm/gaffs/diyprojector.htm
Attachments
: small bulbs vs. large bulbs.
Yes, I realize this, but I was trying to break that barrier. I started out looking for the smallest bulbs possible, but soon realized that it was not really within my budget to do so. Then, somewhere along the line of trying to find a good midpoint of cost vs. size, I got onto the cheap-as-possible kick. And that means going with the big honking 11x4.5" bulbs, which can be had for $20. I bought the $90 setup off ebay because (a) I thought I could use the reflector, and (b) it came with the socket, wiring, and a nice quiet F-can ballast. The ballast, bulb and socket would have run me close to $90 by themselves, so I'm consoling myself on the failure of the reflector by the fact that I kinda got it for nothing. Of course, I could have bought a 400w magnetic ballast for about $40, but I try not to think about that.
: elliptical driving lights
Hmm, a possibility. How do the dimensions of an H3 halogen bulb match up to the dimensions of your bulb? And how much modification would you have to do to the reflector to accomodate this?
I drew up the curves for two different elliptical reflectors last night: one with a 16" focal depth (for placing the LCD before F2) and one with a 6" FD (for placing the LCD after F2). I think either one would work, but the 6" one will probably more closely mimic the original halogen light pattern. At this point, the materials for making the "rectangular" reflector are cheap enough that I will probably make both just to see how they turn out.
If I were working with the smaller 400w bulbs, I might try that 8-1/2" reflector I pointed out earlier. But that's not the track I'm on right now...
I still plan on more-or-less mimicking the OHP setup, with the light on the bottom, a stage with a fresnel above that, LCD on the stage, and a 90deg lens/mirror setup on top. The main difference will be that I will not employ a mirror to reflect light from behind the projector to the stage above. This may cause cooling problems, but I'm going to try to overcome those with airflow.
Yes, I realize this, but I was trying to break that barrier. I started out looking for the smallest bulbs possible, but soon realized that it was not really within my budget to do so. Then, somewhere along the line of trying to find a good midpoint of cost vs. size, I got onto the cheap-as-possible kick. And that means going with the big honking 11x4.5" bulbs, which can be had for $20. I bought the $90 setup off ebay because (a) I thought I could use the reflector, and (b) it came with the socket, wiring, and a nice quiet F-can ballast. The ballast, bulb and socket would have run me close to $90 by themselves, so I'm consoling myself on the failure of the reflector by the fact that I kinda got it for nothing. Of course, I could have bought a 400w magnetic ballast for about $40, but I try not to think about that.
: elliptical driving lights
Hmm, a possibility. How do the dimensions of an H3 halogen bulb match up to the dimensions of your bulb? And how much modification would you have to do to the reflector to accomodate this?
I drew up the curves for two different elliptical reflectors last night: one with a 16" focal depth (for placing the LCD before F2) and one with a 6" FD (for placing the LCD after F2). I think either one would work, but the 6" one will probably more closely mimic the original halogen light pattern. At this point, the materials for making the "rectangular" reflector are cheap enough that I will probably make both just to see how they turn out.
If I were working with the smaller 400w bulbs, I might try that 8-1/2" reflector I pointed out earlier. But that's not the track I'm on right now...
I still plan on more-or-less mimicking the OHP setup, with the light on the bottom, a stage with a fresnel above that, LCD on the stage, and a 90deg lens/mirror setup on top. The main difference will be that I will not employ a mirror to reflect light from behind the projector to the stage above. This may cause cooling problems, but I'm going to try to overcome those with airflow.
Rolm,
Can you tell me where did you find this ? Offline or online? I would love to try that for my large 150W lamp.
- -----------------------------------------------
Hm, if you could go smaller than the 12" diameter you mentioned, you might try this:
6' Cord Clamp Lamp with 8-1/2" Shade
Model: #010-HD277-894
SKU: #277894
--------------------------------------------------------
I was thinking about the two designs of elliptical reflectors and IMHO the second design (LCD outside of F2) will probably give hotspot free even light beam.. particularly when using fresnel before LCD. In order to do the first design, I think you will have to start with a very large reflector so that when you place lcd between F1 and F2, it covers the whole panel..the beam will narrow towards the F2 and you probably need to keep atleast 6-7 inches distance between the lamp and LCD to avoide hotspot/heat issues..considering that distance and counting approx. 10 inch diagonal distance for LCD, your reflector diameter will come around 20inch minimum - just a rough estimation. Now, 20 inch diameter reflector could be hard to make/find. I could be wrong about the reflector diameter calculation but just a thought.
Can you tell me where did you find this ? Offline or online? I would love to try that for my large 150W lamp.
- -----------------------------------------------
Hm, if you could go smaller than the 12" diameter you mentioned, you might try this:
6' Cord Clamp Lamp with 8-1/2" Shade
Model: #010-HD277-894
SKU: #277894
--------------------------------------------------------
I was thinking about the two designs of elliptical reflectors and IMHO the second design (LCD outside of F2) will probably give hotspot free even light beam.. particularly when using fresnel before LCD. In order to do the first design, I think you will have to start with a very large reflector so that when you place lcd between F1 and F2, it covers the whole panel..the beam will narrow towards the F2 and you probably need to keep atleast 6-7 inches distance between the lamp and LCD to avoide hotspot/heat issues..considering that distance and counting approx. 10 inch diagonal distance for LCD, your reflector diameter will come around 20inch minimum - just a rough estimation. Now, 20 inch diameter reflector could be hard to make/find. I could be wrong about the reflector diameter calculation but just a thought.
: 8-1/2" reflector
I bought mine at Home Depot, but any self-respecting hardware store should carry them. It's nothing more than a plastic bulb socket attached to a clamp, and the reflector screws onto it.
: short-FD vs long-FD elliptical reflectors.
I had something of an epiphany while I was tracing the reflector curves: if you follow the curve all the way around to draw a complete ellipsoid, then you can see that F1 and F2 are equadistant from points on the ellipsoid corresponding to the horizontal axis.
<img src="http://members.cox.net/rolm/images/complete_ellipse.jpg">
From this, you can see how the height of the ellipsoid relates to the FD and the height at F1 and F2: the shorter the fd, the smaller the height, up until FD == 0, at which point you have a sphere with diameter == (height at F1).
Academic rather than practical, and pretty simple geometry when you think about it, but it's an interesting illustration. For me, anyways.
Or maybe I have too much time on my hands... :/
I bought mine at Home Depot, but any self-respecting hardware store should carry them. It's nothing more than a plastic bulb socket attached to a clamp, and the reflector screws onto it.
: short-FD vs long-FD elliptical reflectors.
I had something of an epiphany while I was tracing the reflector curves: if you follow the curve all the way around to draw a complete ellipsoid, then you can see that F1 and F2 are equadistant from points on the ellipsoid corresponding to the horizontal axis.
<img src="http://members.cox.net/rolm/images/complete_ellipse.jpg">
From this, you can see how the height of the ellipsoid relates to the FD and the height at F1 and F2: the shorter the fd, the smaller the height, up until FD == 0, at which point you have a sphere with diameter == (height at F1).
Academic rather than practical, and pretty simple geometry when you think about it, but it's an interesting illustration. For me, anyways.
Or maybe I have too much time on my hands... :/
epiphany
Very interesting observation..
I didnt complete the ellipsoidal so missed that part! Simple geometry makes an interesting observation. If the observation is correct (which I think is) than I think the best approach is to go with the design #2 where lcd is outside the F1 and F2 points since hight decreases with FD increase and the idea is to cover the entire LCD within the beam path.
Very interesting observation..
I didnt complete the ellipsoidal so missed that part! Simple geometry makes an interesting observation. If the observation is correct (which I think is) than I think the best approach is to go with the design #2 where lcd is outside the F1 and F2 points since hight decreases with FD increase and the idea is to cover the entire LCD within the beam path.
Well, I built a design2 model, with the LCD after F2. Results were so-so. It's a little brighter than the std OHP, but not greatly so. I can hold a piece of paneling above the reflector and verify that my focal point is where I expect it to be, and the light at the stage/fresnel is quite bright. But not that much more than the OHP.
<img src="http://members.cox.net/rolm/images/mhohp_design_1.jpg">
One possible reason for this is that I have created an elliptical reflector with a too-small FD (I went for 6"), and therefore too great of an angle of beam spread, and the fresnel isn't able to cope with the expanding beam. This theory is supported by the fact that the stage/fresnel throws an awful lot of ambient light into the room (ie light NOT directed upwards), even with a narrow internal apeture.
I'm reconsidering design1, and abandoning the fresnel altogether. I have enough components to construct it, so I think I'll just give it a try. Undream had a similar idea (http://www.dreamlash.com/DIY/may13-2.html), and it looks like it's working pretty well for him.
I have more pictures of the progress, but I'm having a hard time motivating myself to make a page until I have something to show off...
<img src="http://members.cox.net/rolm/images/mhohp_design_1.jpg">
One possible reason for this is that I have created an elliptical reflector with a too-small FD (I went for 6"), and therefore too great of an angle of beam spread, and the fresnel isn't able to cope with the expanding beam. This theory is supported by the fact that the stage/fresnel throws an awful lot of ambient light into the room (ie light NOT directed upwards), even with a narrow internal apeture.
I'm reconsidering design1, and abandoning the fresnel altogether. I have enough components to construct it, so I think I'll just give it a try. Undream had a similar idea (http://www.dreamlash.com/DIY/may13-2.html), and it looks like it's working pretty well for him.
I have more pictures of the progress, but I'm having a hard time motivating myself to make a page until I have something to show off...
How did you make it?
HOw did you make your elliptical reflector? Is it just the one curve (length or Width) based on gunwan's design? just curious.
I found a source (theaterical supply) in SF where I can possibly find some ellipsoidal reflectors made for stage lights. I will go there Monday and hunt for some thing pre made.
Part-express reflector arrived - Its a typical parabolic shape and I dont this it will help with my project but I will try anyway when my lamp arrives.
I was reading about various screens and found out that the glass bead screens are not suitable for LCD projection - less contrast. White matte is the best and if you apply a thin coat of gray color (5%) mixed with gesso (clear) with another coating of some transluscent gesso, the screen gives more contrast (due to gray) and 3D effect (clear coat). I will have to try that.
HOw did you make your elliptical reflector? Is it just the one curve (length or Width) based on gunwan's design? just curious.
I found a source (theaterical supply) in SF where I can possibly find some ellipsoidal reflectors made for stage lights. I will go there Monday and hunt for some thing pre made.
Part-express reflector arrived - Its a typical parabolic shape and I dont this it will help with my project but I will try anyway when my lamp arrives.
I was reading about various screens and found out that the glass bead screens are not suitable for LCD projection - less contrast. White matte is the best and if you apply a thin coat of gray color (5%) mixed with gesso (clear) with another coating of some transluscent gesso, the screen gives more contrast (due to gray) and 3D effect (clear coat). I will have to try that.
Yes, my reflector was just the one curve, based pretty much on Gunwan's method. I experimented with adding side reflectors as well as using a flexible mirrored plastic, but nothing really improved the brightness too much. This lead me to my conclusion that there was something fundamentally wrong with my setup.
I have constructed another much deeper elliptical reflector, this time with a 26" FD. I've made the reflector, but haven't mounted the lamp yet (I hope to do that tonight). I'm trying for design1 on this one. The challenge is to make the reflector large enough to reduce the angle that the light enters the LCD without making the entire projector 6 feet tall. It would be easy to do: due to the diameter of the bulb (4-1/2"), I am forced to make very wide reflectors (this one is 18" wide). Even so, my beam angle is close to 55deg. In this case, F2 is only 5" above the theoretical placement of the 7"-high LCD. This may be too shallow.
The trouble is that trying to increase this height is difficult: I can only do this by either increasing the FD or decreasing the ellipse height. The difference in F2 height above the LCD when I went from a 20" FD to a 26" FD was only 3/4". And the 4-1/2" diameter of the bulb forces me to make the ellipse taller as I increase the FD. If I went with the smaller ($30) 2-1/2"-diam bulb, I could reduce the width of the reflector to around 12" and increase the angle of light passing thru the LCD dramatically, and probably raise F2 another 5". But that means shelling out more $$$, which I'm not willing to do yet.
Hmm, a theatrical store... I'd be interested to know what they have to offer in the realm of elliptical reflectors.
Screens are an area that I have read a fair bit about but haven't experimented that much with: once I get the projector working well, then I may have time to mess with that.
I have constructed another much deeper elliptical reflector, this time with a 26" FD. I've made the reflector, but haven't mounted the lamp yet (I hope to do that tonight). I'm trying for design1 on this one. The challenge is to make the reflector large enough to reduce the angle that the light enters the LCD without making the entire projector 6 feet tall. It would be easy to do: due to the diameter of the bulb (4-1/2"), I am forced to make very wide reflectors (this one is 18" wide). Even so, my beam angle is close to 55deg. In this case, F2 is only 5" above the theoretical placement of the 7"-high LCD. This may be too shallow.
The trouble is that trying to increase this height is difficult: I can only do this by either increasing the FD or decreasing the ellipse height. The difference in F2 height above the LCD when I went from a 20" FD to a 26" FD was only 3/4". And the 4-1/2" diameter of the bulb forces me to make the ellipse taller as I increase the FD. If I went with the smaller ($30) 2-1/2"-diam bulb, I could reduce the width of the reflector to around 12" and increase the angle of light passing thru the LCD dramatically, and probably raise F2 another 5". But that means shelling out more $$$, which I'm not willing to do yet.
Hmm, a theatrical store... I'd be interested to know what they have to offer in the realm of elliptical reflectors.
Screens are an area that I have read a fair bit about but haven't experimented that much with: once I get the projector working well, then I may have time to mess with that.
elliptical (ellipsoidal) reflector
Finally, I got the reflector from the theater supply store. Its indeed a piece of art (see pics) has more than 700 flat mirror like surfaces and according to the literature can reflect up to 90% of the light. Its about 6 inch diameter and around the same height and comes with the cover with approx. 3 inch opening where the beam focuses.
They also had a glass reflector (same dimensions) which reflects all the light but transmit heat so that the bounced light is not hot -if this aluminum reflector works I might upgrade it to the glass one later. Glass reflector can transmit almost all the light and according to the theater people has a very sharp focused beam since it does not have small flat mirror like surfaces of the aluminum one.
Finding F1 for the elliptical reflector was fun. See the next post.
Finally, I got the reflector from the theater supply store. Its indeed a piece of art (see pics) has more than 700 flat mirror like surfaces and according to the literature can reflect up to 90% of the light. Its about 6 inch diameter and around the same height and comes with the cover with approx. 3 inch opening where the beam focuses.
They also had a glass reflector (same dimensions) which reflects all the light but transmit heat so that the bounced light is not hot -if this aluminum reflector works I might upgrade it to the glass one later. Glass reflector can transmit almost all the light and according to the theater people has a very sharp focused beam since it does not have small flat mirror like surfaces of the aluminum one.
Finding F1 for the elliptical reflector was fun. See the next post.
Attachments
ellipsoidal reflector (continue)
To see how the reflector works and where the F1 is, I used a salvaged ballpoint pen with LED light and tryied to mimic the dimension of the MH lamp I plan to use (still have not received - more than a week overdue). The reflector is amazing - I can get a very focused beam (about 2 inch diameter) at the F2 and if I look inside the reflector from F2 I can pretty much see the LED on most of the mirror surfaces. The pictures are not sharp enough since I took them with available light holding the reflector with one hand and my heavy digital SLR on the other so kind of blurry but you can get the idea.
To see how the reflector works and where the F1 is, I used a salvaged ballpoint pen with LED light and tryied to mimic the dimension of the MH lamp I plan to use (still have not received - more than a week overdue). The reflector is amazing - I can get a very focused beam (about 2 inch diameter) at the F2 and if I look inside the reflector from F2 I can pretty much see the LED on most of the mirror surfaces. The pictures are not sharp enough since I took them with available light holding the reflector with one hand and my heavy digital SLR on the other so kind of blurry but you can get the idea.
Attachments
condenser lens
Now I have the reflector and the lamp is on its way, I am thinking of looking into how to expand the focused beam from the reflector. I know other people on the forum have been using a condensor lens to expand the focused light on to the frasnel. In my 3M overhead, it has a halogen lamp with elliptical reflector and the focused light goes through a narrow iris on to the mirror and bounced on the frasnel.
My question is is it necessory to use condenser lens or let the beam to expand itself (like the 3M ohp setup). I dont have anything close to the condensor lens that I can try so any other suggestions?
Now I have the reflector and the lamp is on its way, I am thinking of looking into how to expand the focused beam from the reflector. I know other people on the forum have been using a condensor lens to expand the focused light on to the frasnel. In my 3M overhead, it has a halogen lamp with elliptical reflector and the focused light goes through a narrow iris on to the mirror and bounced on the frasnel.
My question is is it necessory to use condenser lens or let the beam to expand itself (like the 3M ohp setup). I dont have anything close to the condensor lens that I can try so any other suggestions?
WOW! That's a pretty kick-A reflector! Nice job figuring out the F1/F2, also.
I think that people use and "atomoshperic" or "condenser" lens when they want to change the angle at which the beam expands in order to bring F2 closer or push it farther away. My OHP also omittted the condenser lens, so I think that's a pretty common way of doing it.
On the other hand, I don't know whether or not a condenser lens performs other magic on the beam, like evening it out and reducing hotspots. I don't think so, but perhaps.
Unfortunately, the bulb that I'm working with is the el-cheapo 4-1/2"-diameter one, so a 6" reflector is too small. I ended up building 4 different reflectors, each more complex then the last. None of them managed to give me a clean, clear beam: most weren't much better than the bulb with nothing more than cardboard boxing it in.
I think I'm ready to abandon trying to build a "rectangular reflector, because I think they waste too much of the available light. I'm taking a step back and eying the metal bowls like you talked about very early in this thread. I found a source for mixer bowls, which elliptically shaped, and usually about 8-10" in diameter and 10-12" deep. The ones I found are stainless steel, so they should be resonably shiny to start with, and should polish up nicely.
They're cheap (around $20), so I'll order one this week to play around with. I may even pick up a cheap aluminum spherical mixing bowl this weekend to build the alpha test kit.
Again, good job with the reflector. If I decide to go down a bulb size, I think I'll definitely have to find one of those.
I think that people use and "atomoshperic" or "condenser" lens when they want to change the angle at which the beam expands in order to bring F2 closer or push it farther away. My OHP also omittted the condenser lens, so I think that's a pretty common way of doing it.
On the other hand, I don't know whether or not a condenser lens performs other magic on the beam, like evening it out and reducing hotspots. I don't think so, but perhaps.
Unfortunately, the bulb that I'm working with is the el-cheapo 4-1/2"-diameter one, so a 6" reflector is too small. I ended up building 4 different reflectors, each more complex then the last. None of them managed to give me a clean, clear beam: most weren't much better than the bulb with nothing more than cardboard boxing it in.
I think I'm ready to abandon trying to build a "rectangular reflector, because I think they waste too much of the available light. I'm taking a step back and eying the metal bowls like you talked about very early in this thread. I found a source for mixer bowls, which elliptically shaped, and usually about 8-10" in diameter and 10-12" deep. The ones I found are stainless steel, so they should be resonably shiny to start with, and should polish up nicely.
They're cheap (around $20), so I'll order one this week to play around with. I may even pick up a cheap aluminum spherical mixing bowl this weekend to build the alpha test kit.
Again, good job with the reflector. If I decide to go down a bulb size, I think I'll definitely have to find one of those.
my reflector
I havent worked out the focals ..just some "eyeball" tests. I'm using the giant 4 1/2 inch HID, I located some dirt cheap bowls. The reflector is 13 3/4 wide by about 7 inchs deep $7.00, it seems to give really good direction to the light, the second is 12 1/4 by 6 inchs deep $5.00. The second failed as a reflector, but seeing the stage reflector I'm wondering if there is benefit in using the failed bowl to close the "clam shell" on the out put side of the lamp housing. Also does anyone know how an HID likes to have it's light rays reflected back to it's arc tube? Not to mention cooling...
any thoughts?
zardoz
I havent worked out the focals ..just some "eyeball" tests. I'm using the giant 4 1/2 inch HID, I located some dirt cheap bowls. The reflector is 13 3/4 wide by about 7 inchs deep $7.00, it seems to give really good direction to the light, the second is 12 1/4 by 6 inchs deep $5.00. The second failed as a reflector, but seeing the stage reflector I'm wondering if there is benefit in using the failed bowl to close the "clam shell" on the out put side of the lamp housing. Also does anyone know how an HID likes to have it's light rays reflected back to it's arc tube? Not to mention cooling...
any thoughts?
zardoz
<b>>clamshell bowls</b>
As far as I know, the clamshell arrangement is only beneficial for an elliptical reflector, where the rearward reflector (where the bulb is mounted) is an elliptical reflector (as opposed to a parabolic or spherical), and the apeture in the forward bowl corresponds to the F2 of the rearward bowl. The second "bowl" serves more to block errant rays that are not in line with the focused beam passing thru F2.
I can't think of of how a clamshell arrangement would benefit a parabolic reflector (where the reflector only serves to spread the beam) or a spherical reflector (where the refl. sends the beam straight out).
Sooo, where'd ya find the cheap bowls? I found a pretty-much elliptical reflector on ebay, in the form of a refubished Kitchenaide mixer bowl.
As far as I know, the clamshell arrangement is only beneficial for an elliptical reflector, where the rearward reflector (where the bulb is mounted) is an elliptical reflector (as opposed to a parabolic or spherical), and the apeture in the forward bowl corresponds to the F2 of the rearward bowl. The second "bowl" serves more to block errant rays that are not in line with the focused beam passing thru F2.
I can't think of of how a clamshell arrangement would benefit a parabolic reflector (where the reflector only serves to spread the beam) or a spherical reflector (where the refl. sends the beam straight out).
Sooo, where'd ya find the cheap bowls? I found a pretty-much elliptical reflector on ebay, in the form of a refubished Kitchenaide mixer bowl.
Rolm
I got these at the local "bargain department store" Saan's in nova scotia. They are stainless stell and wicked shiny! The larger bowl is somewhat eliptical, I've spent most of my time working out how to feed my laptop panel so havent done a lot of work on the reflector yet. Still learing 😉
zardoz
I got these at the local "bargain department store" Saan's in nova scotia. They are stainless stell and wicked shiny! The larger bowl is somewhat eliptical, I've spent most of my time working out how to feed my laptop panel so havent done a lot of work on the reflector yet. Still learing 😉
zardoz
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