Hello All,
I looked around the boards i saw some info on this subject but I didnt see what i was looking for. YES I understand that bulbs can be retrofited. but can they be retrofited with 1000 watt MH bulbs, if so, do you need a reflector?
I ask this because im thinking that a MH kit would be too big to fit IN an OHP.
If OHPs can be retrofitted this way then i am DEFINITELY going to buy a cheap POS low lumen OHP and retrofitt it and possibly use the reflector it come with 🙂
Thanks.
-JimmY-
I looked around the boards i saw some info on this subject but I didnt see what i was looking for. YES I understand that bulbs can be retrofited. but can they be retrofited with 1000 watt MH bulbs, if so, do you need a reflector?
I ask this because im thinking that a MH kit would be too big to fit IN an OHP.
If OHPs can be retrofitted this way then i am DEFINITELY going to buy a cheap POS low lumen OHP and retrofitt it and possibly use the reflector it come with 🙂
Thanks.
-JimmY-
heres a thought...how about retrofitting OHPs with LOAs. one LOA in theory SHOULD work how about TWO LOAs.
Is it me or that a GREAT idea?
Is it me or that a GREAT idea?
I originally tried several different methods of re-creating a "focused" 400W MH light source and traditional OHP optics. Several times I failed, with the light passing thru the OHP stage insufficient to throw a decently bright image.
I finally succeeded by optimising size vs output and settling on a 20K lumen 250W HQI MH bulb, and installing it in such a way that it essentially took the place of the original 360W halogen. That is, I re-used the EXACT optics of the OHP, including the 2"-diameter reflector behind the original lamp. Outline of the project can be seen <a href="http://members.cox.net/rolm/update/">here</a>.
The other failed experiments were done using a standard 11"x4.5" 400W MH bulb. Due to the size of the bulb, I was never truly able to make a reflector that fit the confines of a standard OHP box, and so I was never able to re-use the EXACT OHP optics. This, I believe, was the primary reason for the previous failures and the current success.
In my understanding, the one outstanding issue is the fact that the LCD only passes _polarized_ light (or close to it), meaning that most of the light falling on the LCD does not pass thru it. Just plopping a huge bulb in the bottom of an OHP box with no reflector results in alot of unfocused light bouncing around (and causing light interference) before it passes thru the LCD, vastly reducing the amount of "usable" lumens.
My 2 cents.
I finally succeeded by optimising size vs output and settling on a 20K lumen 250W HQI MH bulb, and installing it in such a way that it essentially took the place of the original 360W halogen. That is, I re-used the EXACT optics of the OHP, including the 2"-diameter reflector behind the original lamp. Outline of the project can be seen <a href="http://members.cox.net/rolm/update/">here</a>.
The other failed experiments were done using a standard 11"x4.5" 400W MH bulb. Due to the size of the bulb, I was never truly able to make a reflector that fit the confines of a standard OHP box, and so I was never able to re-use the EXACT OHP optics. This, I believe, was the primary reason for the previous failures and the current success.
In my understanding, the one outstanding issue is the fact that the LCD only passes _polarized_ light (or close to it), meaning that most of the light falling on the LCD does not pass thru it. Just plopping a huge bulb in the bottom of an OHP box with no reflector results in alot of unfocused light bouncing around (and causing light interference) before it passes thru the LCD, vastly reducing the amount of "usable" lumens.
My 2 cents.
WOW!!! AMAZING post! thank you. your site is great and very informative, i've learned alot from this. i dont know if you have info on this but do you think its possible to use LOAs? i never thought a 250 watt bulb would EVER be able to power this project...im still wondering how this is possible...
this project is great but the biggest for me is the price
the 40$ bulb i cant afford but the 125$ ballast...i dont even know what a ballast IS is it even necessary?
im on a 350$ budget from Christmas, i leaned towards the Zark projector and i bought an LCD from partsexpress and i ordered and artograph and i canceled it, can i use the LCd from parts express with an OHP?
and again i would like to thank you for your professional reply and your pix look AMAZING!!! if mine is HALF as nice as yours i will be satisfied. 🙂
-JimmY-
this project is great but the biggest for me is the price
the 40$ bulb i cant afford but the 125$ ballast...i dont even know what a ballast IS is it even necessary?
im on a 350$ budget from Christmas, i leaned towards the Zark projector and i bought an LCD from partsexpress and i ordered and artograph and i canceled it, can i use the LCd from parts express with an OHP?
and again i would like to thank you for your professional reply and your pix look AMAZING!!! if mine is HALF as nice as yours i will be satisfied. 🙂
-JimmY-
RE: LOAs vs MH
Some people have had good luck using LOAs, others not so much. I have 2 LOAs that I use to light part of a workshop, and my preliminary experiments with them gave me the impression that they would not work very well for my purposes.
Without starting a holy war, the biggest handicap for LOAs is the fact that they generate a very diffuse light, whereas LCDs require polarized light.
RE: ballasts
A ballast is what 'drives' a metal halide lamp. HID lamps have very different characteristics than the typical household light bulb. A detailed outline that describes them far better than I can <a href="http://www.ballastdesign.com/overview.html"> is found here</a>.
Suffice it to say that yes, the ballast is absolutely necessary.
That being said, the ballast/lamp combination that I'm using here is about the most expensive way to go. (This is because I'm using a specific sort of bulb, because I was trying to replicate someone else's work.) It is possible to find non-electronic ballasts for a <b>standard</b> 250W MH lamp for much less, but finding the bulbs with the correct dimensions for this particular application gets more difficult.
I am currently exploring the possibilities of replicating this OHP mod using a MH bulb/ballast combo for less than $100. I will post here if I find it.
Some people have had good luck using LOAs, others not so much. I have 2 LOAs that I use to light part of a workshop, and my preliminary experiments with them gave me the impression that they would not work very well for my purposes.
Without starting a holy war, the biggest handicap for LOAs is the fact that they generate a very diffuse light, whereas LCDs require polarized light.
RE: ballasts
A ballast is what 'drives' a metal halide lamp. HID lamps have very different characteristics than the typical household light bulb. A detailed outline that describes them far better than I can <a href="http://www.ballastdesign.com/overview.html"> is found here</a>.
Suffice it to say that yes, the ballast is absolutely necessary.
That being said, the ballast/lamp combination that I'm using here is about the most expensive way to go. (This is because I'm using a specific sort of bulb, because I was trying to replicate someone else's work.) It is possible to find non-electronic ballasts for a <b>standard</b> 250W MH lamp for much less, but finding the bulbs with the correct dimensions for this particular application gets more difficult.
I am currently exploring the possibilities of replicating this OHP mod using a MH bulb/ballast combo for less than $100. I will post here if I find it.
great, i will definitely take your advice and move forward from there,i will search for a standard 250 watt solution i hope it will be poerful enough. i look forward to your progress.feel free to keep me informed 🙂.goo luck.
thanks.
jimmy.
thanks.
jimmy.
The bulb was a MH-DE250/TD/4K from <a href="http://www.bulb-source.com/MHDoubleEnded.htm">bulb source</a>.
Just to make sure everyone is aware, this was an HQI setup, which is not widely available in the US. Specifically, the HQI bulb uses a different (MUCH higher) starting voltage, and therefore you need a much more expensive ballast.
The only reason I used this was (a) I was trying to replicate as closely as I could <b>ywh</b>'s design, and (b) I got the ballast on sale for about 75% of what it would usually cost.
Just to make sure everyone is aware, this was an HQI setup, which is not widely available in the US. Specifically, the HQI bulb uses a different (MUCH higher) starting voltage, and therefore you need a much more expensive ballast.
The only reason I used this was (a) I was trying to replicate as closely as I could <b>ywh</b>'s design, and (b) I got the ballast on sale for about 75% of what it would usually cost.
Question for Rolm
Rolm, are you looking (for your single ended option) at using the smaller G12 base single ended bulbs for this option? Or the larger medium base versions? I've been looking around for them and it appears the G12 base version is smaller in diameter (3/4 inch) and length than the medium base version. I have an older OHP similar to the one you modded first (metal casing, large fan, but mine has a 600W halogen in it) and I'm looking at your and YHW's setup as to where I'd like to advance to. You were mentioning that 250w's from the metal halide may be washing out your contrast ratio? The reason I'm asking, I already have my hands on a 400w (M59) ballast and I was hoping that I could use it in conjunction with a 400w single ended bulb to upgrade my unit. However, if you're having problems with 250w of Metal halide, I could have even more problems with the 400w. (Also, I'm not sure I could find a 400w bulb in the smaller G12 base (double pin) single ended style). I guess what I'm asking is whether (in your experiences with this) there might be a upper limit on the wattage of this type of setup and that it might be better to stay under 250w to avoid "over powering" a good picture? (Hope this makes sense
) Thanks, Smoke Eater
Rolm, are you looking (for your single ended option) at using the smaller G12 base single ended bulbs for this option? Or the larger medium base versions? I've been looking around for them and it appears the G12 base version is smaller in diameter (3/4 inch) and length than the medium base version. I have an older OHP similar to the one you modded first (metal casing, large fan, but mine has a 600W halogen in it) and I'm looking at your and YHW's setup as to where I'd like to advance to. You were mentioning that 250w's from the metal halide may be washing out your contrast ratio? The reason I'm asking, I already have my hands on a 400w (M59) ballast and I was hoping that I could use it in conjunction with a 400w single ended bulb to upgrade my unit. However, if you're having problems with 250w of Metal halide, I could have even more problems with the 400w. (Also, I'm not sure I could find a 400w bulb in the smaller G12 base (double pin) single ended style). I guess what I'm asking is whether (in your experiences with this) there might be a upper limit on the wattage of this type of setup and that it might be better to stay under 250w to avoid "over powering" a good picture? (Hope this makes sense
) Thanks, Smoke EaterSmoke Eater-
I am looking at all possibilities. I haven't been able to find a decently priced 400W MH bulb with the proper dimensions (ie <= 1" diameter) to try this out on. I wouldn't want to spend more than $50 on a bulb at this point. That being said, 400W is where I would like to go with this.
The OHP that I modded also originally came with the 600W halogon, probably much like the one you have.
I think that the wash-out is probably caused by the color temp of the 250W bulb (10,000K). A more ideal color temp would be about 5,000K.
I'm no longer sure that the LCD is getting overpowered. I watched much of LOTR a few nights ago, and there were some scenes that (a) appeared too dark and murky on the screen, but (b) details were clearer if you looked at the LCD directly. This tells me that either (a) I should try to put more light out, or (b) the optics (and esp light leakage) of the OHP needs to be tinkered with.
My personal next step is going to be to mess around with some aspheric condenser lenses to see if I can increase the amount of light getting to the stage. This is the only real difference between mine and <b>ywh</b>'s setup at this point (aside from the actual LCDs), and IMHO his results are still far better than mine.
I am looking at all possibilities. I haven't been able to find a decently priced 400W MH bulb with the proper dimensions (ie <= 1" diameter) to try this out on. I wouldn't want to spend more than $50 on a bulb at this point. That being said, 400W is where I would like to go with this.
The OHP that I modded also originally came with the 600W halogon, probably much like the one you have.
I think that the wash-out is probably caused by the color temp of the 250W bulb (10,000K). A more ideal color temp would be about 5,000K.
I'm no longer sure that the LCD is getting overpowered. I watched much of LOTR a few nights ago, and there were some scenes that (a) appeared too dark and murky on the screen, but (b) details were clearer if you looked at the LCD directly. This tells me that either (a) I should try to put more light out, or (b) the optics (and esp light leakage) of the OHP needs to be tinkered with.
My personal next step is going to be to mess around with some aspheric condenser lenses to see if I can increase the amount of light getting to the stage. This is the only real difference between mine and <b>ywh</b>'s setup at this point (aside from the actual LCDs), and IMHO his results are still far better than mine.
Rolm, I'm still amazed at your site. and i've decided to buy an APOLLO 1000 just like yours and i also plan to retrofit it.But i dont not plan to retrofit it with HQI's this is MUCH too expensive to me at this time. I read at the bottom of your page that it is possible to use standard 250 MH bulbs, And im am serously considering buying one but since you havent tried this and i havent seen anyone who tried this im feeling a bit indecisive on what to do.
when i first read your post about using 250 watt HQIs i didnt understand how that was possible but now i think i have a guess...since 360 watt bulbs have less lumens than a HQI then an HQI would be better, i didnt understand this at first and after carefully reviewing your site and YWH's i came to the conclusion that its not about how many watts it is, its REALLY about the lumens.
ROLM, if you are ever on AIM please IM me.
Thank you
jimmy
when i first read your post about using 250 watt HQIs i didnt understand how that was possible but now i think i have a guess...since 360 watt bulbs have less lumens than a HQI then an HQI would be better, i didnt understand this at first and after carefully reviewing your site and YWH's i came to the conclusion that its not about how many watts it is, its REALLY about the lumens.
ROLM, if you are ever on AIM please IM me.
Thank you
jimmy
Yep, the wattage is measure of the amount of power the lamp consumes, NOT the amount of light it puts out.
I haven't had much luch finding cheap alternatives to the HQI setup as of yet, but I'm still looking.
I haven't had much luch finding cheap alternatives to the HQI setup as of yet, but I'm still looking.
have you tried the standard 250 watt MH yet?
I read that you are interested with working wiht 400 watt MH bulbs, wouldnt that be too big?
Please keep me updated on yout non HQI progress, I hope thats not too much to ask.
"(3) perhaps try to mod the AI-15000 with a cheaper single-ended MH bulb/ballast without losing lumens."
this would be intersting to see.
Thank you very much for your replies.
Jimmy
I read that you are interested with working wiht 400 watt MH bulbs, wouldnt that be too big?
Please keep me updated on yout non HQI progress, I hope thats not too much to ask.
"(3) perhaps try to mod the AI-15000 with a cheaper single-ended MH bulb/ballast without losing lumens."
this would be intersting to see.
Thank you very much for your replies.
Jimmy
ROLM, I noticed that you did not use a condenser lense do you think the picture quality would of been better if you used a condenser lense? Maybe this was the reason for your problems earlier.
I've found a 400 watt MH bulb which they claim is smaller http://www.bulbco.com/methalredsiz.html i hope this is the MH you where looking for...BUT its pricey..
one more thing, do you think TUBULAR MH bulbs will work for this project?
Thank You.
Jimmy
I've found a 400 watt MH bulb which they claim is smaller http://www.bulbco.com/methalredsiz.html i hope this is the MH you where looking for...BUT its pricey..
one more thing, do you think TUBULAR MH bulbs will work for this project?
Thank You.
Jimmy
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