Don't worry, I'm not trying to sell a half finished project or one of those evil plastic TV enlarging lenses!!
I work in a small theatre as a technician operating sound and lighting equipment, and also a 35mm cinema projector. One effect common in TV and theatrical lighting is to use what is known as a 'profile spot' to project a gobo ( a metal or glass disc with a pattern or picture on it ) onto the stage. I think a profile could be used to make a simple, cheap projector.
Starting from the rear of a typical profile, we have the reflector and lamp. It is usually possible to move the lamp in relation to the reflector so that the beam from the lamp is as even as possible. Many profiles also have a condensor lens just in front of the lamp to increase light output. Lamps (DON'T CALL THEM BULBS!!! BULBS ARE WHAT YOU PLANT IN YOUR GARDEN!!!!!) range from 200 watt tungsten halogen upto 1200 watt HMI and beyond.
In front of the lamp assembly is where the gobo sits, along with shutters which can be used to control the shape of the beam. More on this later..
Next we have the lens tube, which consists of two large glass convex lenses which can be moved backwards and forwards to adjust the size and focus of the beam. Beam angles can range from 5 degrees upto 45 degrees, though each lens tube will only cover about 10-15 degrees of adjustment.
Now for the intersting bit! Rather than build a video projector entirely from scratch, if we take out the gobo and shutters and replace them with a small LCD screen, we would have a very easy to build projector. All of the hard work has already been done. The lamp, reflector and lenses are already mounted in an enclosure. The ability to zoom in and out is built in. The lenses are solid glass and not Fresnel lenses, so we wont get any artifacts from the rings associated with a Fresnel lens. If we use an ETC Source 4 Zoom, its reflector is designed to reduce transmitted infra red (i.e heat) by about 90%. Result!!
Obviously there are going to be one or two problems with this approach. The first and most important is the screen size. The biggest gobos in general use are 75mm in diameter so we could realistically only use a 75mm (3 inch) screen. We could go bigger by using a followspot which is basically an overgrown profile, but they can easily be 4 feet long or more. We could get around this by standing it on end and having a mirror at 45 degrees on top, but its still going to be quite big.
Despite these problems, I think building a projector using a profile would be an excellent introduction to DIY projectors. The cost of the parts isn't going to be astronomical if you buy them secondhand. I am in the process of getting all the parts together to build my own projector. I've found a portable LCD tv on ebay, and I know some places where I can get profiles from quite cheaply. Altogether I think this project will cost me no more than £100 or so, probably less. I'll let you all know how I get on but don't expect any major developments soon as I am currently moving house 🙂
If you want to build your own, look for a profile of around 1000-1200 watts as these have bigger lenses and can take the largest gobos. You could always fit a lower wattage lamp if you need to. Names to look out for are ADB, ETC Source 4 Zoom, Strand Cantata, Robert Juliat ( if you want to use a folowspot ), CCT Freedom.
I work in a small theatre as a technician operating sound and lighting equipment, and also a 35mm cinema projector. One effect common in TV and theatrical lighting is to use what is known as a 'profile spot' to project a gobo ( a metal or glass disc with a pattern or picture on it ) onto the stage. I think a profile could be used to make a simple, cheap projector.
Starting from the rear of a typical profile, we have the reflector and lamp. It is usually possible to move the lamp in relation to the reflector so that the beam from the lamp is as even as possible. Many profiles also have a condensor lens just in front of the lamp to increase light output. Lamps (DON'T CALL THEM BULBS!!! BULBS ARE WHAT YOU PLANT IN YOUR GARDEN!!!!!) range from 200 watt tungsten halogen upto 1200 watt HMI and beyond.
In front of the lamp assembly is where the gobo sits, along with shutters which can be used to control the shape of the beam. More on this later..
Next we have the lens tube, which consists of two large glass convex lenses which can be moved backwards and forwards to adjust the size and focus of the beam. Beam angles can range from 5 degrees upto 45 degrees, though each lens tube will only cover about 10-15 degrees of adjustment.
Now for the intersting bit! Rather than build a video projector entirely from scratch, if we take out the gobo and shutters and replace them with a small LCD screen, we would have a very easy to build projector. All of the hard work has already been done. The lamp, reflector and lenses are already mounted in an enclosure. The ability to zoom in and out is built in. The lenses are solid glass and not Fresnel lenses, so we wont get any artifacts from the rings associated with a Fresnel lens. If we use an ETC Source 4 Zoom, its reflector is designed to reduce transmitted infra red (i.e heat) by about 90%. Result!!
Obviously there are going to be one or two problems with this approach. The first and most important is the screen size. The biggest gobos in general use are 75mm in diameter so we could realistically only use a 75mm (3 inch) screen. We could go bigger by using a followspot which is basically an overgrown profile, but they can easily be 4 feet long or more. We could get around this by standing it on end and having a mirror at 45 degrees on top, but its still going to be quite big.
Despite these problems, I think building a projector using a profile would be an excellent introduction to DIY projectors. The cost of the parts isn't going to be astronomical if you buy them secondhand. I am in the process of getting all the parts together to build my own projector. I've found a portable LCD tv on ebay, and I know some places where I can get profiles from quite cheaply. Altogether I think this project will cost me no more than £100 or so, probably less. I'll let you all know how I get on but don't expect any major developments soon as I am currently moving house 🙂
If you want to build your own, look for a profile of around 1000-1200 watts as these have bigger lenses and can take the largest gobos. You could always fit a lower wattage lamp if you need to. Names to look out for are ADB, ETC Source 4 Zoom, Strand Cantata, Robert Juliat ( if you want to use a folowspot ), CCT Freedom.
The resolution of readily available LCDs in such a small size tends to be limited. They're not going to be good for a very large picture, and useless with a computer.
I'm guessing the focusing system in those also has no kind of correction for image distortions, since it is projecting only light. Once you project your LCD through that sytem, I bet you'll find the image to be very distorted with barreling. U might get lucky and find that the lens system does have a decently useable range, but I doubt any 2 lens zoom sytem can project much more than a single color without making it look screwy.
If you have easy access to the parts, by all means go for it, I'd be interested to see some pictures of the things you're talking about. I suspect you'll have to get a different objective lens though.
Good Luck
I'm guessing the focusing system in those also has no kind of correction for image distortions, since it is projecting only light. Once you project your LCD through that sytem, I bet you'll find the image to be very distorted with barreling. U might get lucky and find that the lens system does have a decently useable range, but I doubt any 2 lens zoom sytem can project much more than a single color without making it look screwy.
If you have easy access to the parts, by all means go for it, I'd be interested to see some pictures of the things you're talking about. I suspect you'll have to get a different objective lens though.
Good Luck
Who might that be aimed at? i dont see anyone selling a half finnished project, as for your idea i think the zoom lens is obvious in the above post, also the lcd resolutions of a lcd in that size range, another thing to keep in mind is the heat, a reflector with ir filter built into the reflector will only reduce the heat in the reflected light, not the light coming from the front of the source, that can be fixed with a cold mirror or a clear 0deg ir filter but even with that being said u wont remove enough heat with a 1200w hmi in there or any halogen over 500w being so close to the lcd, also with this being a spot system the image wont be big, even with a triplet lens on the end of it the image cant get big because the light is so concentrated into a narrow beam it will stay a narrow beam, thats a big prob that will take abit more work then to just put a projection lens in the front of it, u would need a high powerd projection lens with an extreamly short throw to match, if u can get it to match and of the size of the lcd.
Trev
W
willie
gees relax Trev...everytime someone mentions anything about selling something you get paranoid... 
heya willie im not worried about who sells what as im not in it for the money, but i was curious as to who has a projector for sale thats not finnished, i found the remark quite rude especially from a guy thats been in here 5mins, weather its aimed at me or others it doesnt matter, if it was a joke it should have been realy stated as a joke, but yeah i need a holiday lol.
Trev
@faithblided - I don't think the image will distort as I have used profiles to project gobos (which are basically metal slides) without distorting. Have a look some of the glass gobos on the DHA website ( http://www.dhalighting.co.uk ). These are very detailed, some near photographic quality.
@ace3000_1 - Relax! I wasn't aiming my comment about half-finished projects at anyone on these forums. I think you should read the entire sentence again and not quote only half of it. If my comment was aimed at anyone, it was aimed at those people who sell cheap plastic fresnel lenses to make a projector out of a normal television.
I wasn't suggesting that anyone actually use a 1200w HMI, merely saying that that is how big some profiles can be. A lamp that large would be useful if you wanted to project onto a 30' screen, but its a bit large for home use.
I think the beam will be large enough and the throw short enough to get a good size image. If my calculations are correct, with a 30 degree beam, the image will be 5'4" from corner to corner if the projector is 10' from the screen.
@ace3000_1 - Relax! I wasn't aiming my comment about half-finished projects at anyone on these forums. I think you should read the entire sentence again and not quote only half of it. If my comment was aimed at anyone, it was aimed at those people who sell cheap plastic fresnel lenses to make a projector out of a normal television.
I wasn't suggesting that anyone actually use a 1200w HMI, merely saying that that is how big some profiles can be. A lamp that large would be useful if you wanted to project onto a 30' screen, but its a bit large for home use.
I think the beam will be large enough and the throw short enough to get a good size image. If my calculations are correct, with a 30 degree beam, the image will be 5'4" from corner to corner if the projector is 10' from the screen.
how about a slide projector? It is small, could have a zoom lens, cheap and available to many people. Just add a $1000 + 1.5" LCD. By the way, this idea is as old as this forum.
on the easy part, I cannot see how could this is easier than put an LCD panel onto an OHP. even stripping a LCD monitor wont be more difficult than finding a small size LCD screen. Plus, will it be easy to find a "profiler"?
on the easy part, I cannot see how could this is easier than put an LCD panel onto an OHP. even stripping a LCD monitor wont be more difficult than finding a small size LCD screen. Plus, will it be easy to find a "profiler"?
Profiles are quite easy to find, if you know what you are looking for 🙂 On ebay in the UK, someone is selling 20 CCT Minuette profiles all starting at £25.
The LCD size for the Minuettes would need to be 2", and the larger profiles can accept LCDs of 3" or more. These are larger and cheaper than the $1000 1.5" display that you suggest. Of course, with all of these small screens the resolution is nowhere near as high as the larger LCDs. I am not suggesting that they would be, or that by using a profile and a small display one could build a world-beating video projector very cheaply.
When I said that using a profile would be easy, I meant that the lamp and lenses come in a ready made enclosure with the ability to zoom. I realise that stripping even a small LCD and getting it to a point where it could be used in a projector isn't easy. But on the other hand if the LCD were to get damaged, it won't cost much to replace.
If anyone is interested, I can set up a profile and gobo at work and project it onto our cinema screen and take some photos of it. I can also take photos of a profile so you can see what they are like.
The LCD size for the Minuettes would need to be 2", and the larger profiles can accept LCDs of 3" or more. These are larger and cheaper than the $1000 1.5" display that you suggest. Of course, with all of these small screens the resolution is nowhere near as high as the larger LCDs. I am not suggesting that they would be, or that by using a profile and a small display one could build a world-beating video projector very cheaply.
When I said that using a profile would be easy, I meant that the lamp and lenses come in a ready made enclosure with the ability to zoom. I realise that stripping even a small LCD and getting it to a point where it could be used in a projector isn't easy. But on the other hand if the LCD were to get damaged, it won't cost much to replace.
If anyone is interested, I can set up a profile and gobo at work and project it onto our cinema screen and take some photos of it. I can also take photos of a profile so you can see what they are like.
Go for it mate
What have you got to lose? Just time and a bit of cash.
Hey, you never know, if it does produce good results some of our American friends may have to develop a taste for a little humble pie....
Heh! not long now until they realise the error of their ways and ask to be taken back into the British Empire
SERIOUSLY THOUGH, it will be good to see your results, I at least look forward to seeing them.
Good luck.
What have you got to lose? Just time and a bit of cash.
Hey, you never know, if it does produce good results some of our American friends may have to develop a taste for a little humble pie....
Heh! not long now until they realise the error of their ways and ask to be taken back into the British Empire
SERIOUSLY THOUGH, it will be good to see your results, I at least look forward to seeing them.
Good luck.
gyro
lcd's of 2 and 3inches have resolutions beyond watchable means, people would go out and make a projector with these and be nothing but disapointed with not only the brightness but the quality of the reso, beleive me people have done it, its all in here in the forum, slide projectors u name it, its been done, but not yet a globo imo, but when u think about it at the end of the day if your going to mess with a 2inch lcd, just get a slide projector off of ebay typically 5pounds and put a 2inch lcd in it lol, its the same thing but with the light rays in the right way round, im not having a digg at your idea but i just dont see its practical to use a globo nor cheaper in such a simple setup, with your results place 2 peices of polariser and make sure u have around 10% of the light projected because a lcd will only transmit around 10% of the lights source and thats why u need such a powerful light to get a semi decent lit image, not sure if your aware of that.
Trev
lcd's of 2 and 3inches have resolutions beyond watchable means, people would go out and make a projector with these and be nothing but disapointed with not only the brightness but the quality of the reso, beleive me people have done it, its all in here in the forum, slide projectors u name it, its been done, but not yet a globo imo, but when u think about it at the end of the day if your going to mess with a 2inch lcd, just get a slide projector off of ebay typically 5pounds and put a 2inch lcd in it lol, its the same thing but with the light rays in the right way round, im not having a digg at your idea but i just dont see its practical to use a globo nor cheaper in such a simple setup, with your results place 2 peices of polariser and make sure u have around 10% of the light projected because a lcd will only transmit around 10% of the lights source and thats why u need such a powerful light to get a semi decent lit image, not sure if your aware of that.
Trev
Re: gyro
what do you mean by this?
I know that I will need a powerful light source. Here are some specs for an ETC Source 4 profile :
Bright and cool!
what do you mean by this?
I know that I will need a powerful light source. Here are some specs for an ETC Source 4 profile :
Bright and cool!
I work with source fours every day there are 750W and 1000W bulbs for them and they produce enough heat to turn steel gobos blue so I think a little lcd just might get fried. Halogen is way too hot imo. These metal halide intelligent lights like vari-lites seem like a better idea but even broken ones are way expensive.
gyro_gearloose, I work with high-end lighting (www.highend.com) so I'm fimilar with what your trying to do. However, I dont think you realize why people use 15" LCD's in large enclosures.
Your not going to find an LCD with a high enough resolution the size of a gobo. Not gonna happen unless your buying thousands of units at a time... which I doubt. Your talking about using lcd panels of 1-3" TOPS! Good luck finding them... as those portable TV or LCD's arent gonna cut it. The resolution is way too low! as you'll soon find out if you project one of them. Can you say screen door? 🙂 If we had LCD's that small with the resolution to go with it we'd have a lot less problems.
A majority of the people building units go for 15" panels and higher due to price and resolution advantage. It's the best overall buy right now. I know the 7" widescreen project is getting popular... but even they cant stand up to the 15's and 17's being worked on when it comes to resolution.
However, I do think that projects like Ace's 7" widescreen could benefit from the light engine in such units. Elliptical reflectors, smaller, brighter lamps etc. However, as you know the lamp life doesnt last very long. 2-5000 hours usually. Good, better then some commercial units... but when you consider some people use bulbs that last upwards of 20,000 hours... it's not very good at all.
Believe me... I know what your trying to do and the way your thinking... but I think you should research the LCD's being used in this project before trying anything.
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Your not going to find an LCD with a high enough resolution the size of a gobo. Not gonna happen unless your buying thousands of units at a time... which I doubt. Your talking about using lcd panels of 1-3" TOPS! Good luck finding them... as those portable TV or LCD's arent gonna cut it. The resolution is way too low! as you'll soon find out if you project one of them. Can you say screen door? 🙂 If we had LCD's that small with the resolution to go with it we'd have a lot less problems.
A majority of the people building units go for 15" panels and higher due to price and resolution advantage. It's the best overall buy right now. I know the 7" widescreen project is getting popular... but even they cant stand up to the 15's and 17's being worked on when it comes to resolution.
However, I do think that projects like Ace's 7" widescreen could benefit from the light engine in such units. Elliptical reflectors, smaller, brighter lamps etc. However, as you know the lamp life doesnt last very long. 2-5000 hours usually. Good, better then some commercial units... but when you consider some people use bulbs that last upwards of 20,000 hours... it's not very good at all.
Believe me... I know what your trying to do and the way your thinking... but I think you should research the LCD's being used in this project before trying anything.
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soon
The pricey ones do, the cheaper use parabolic reflectors, the only thing i could gain from one of them is the eliptical reflector, but with that said i could buy a eliptical reflector on its own cheaper then buying the whole globo.
Trev
What i meant by this is for the globos that dont use the eliptical reflector the light is paralelle, we want paralelle light only to the lcd, not after it or before the first collimating lens.
are these the lights they use in nite clubs?
anyone know how bright this light is? http://www.dhalighting.co.uk/images/projector1.jpg
anyone know how bright this light is? http://www.dhalighting.co.uk/images/projector1.jpg
Ace, you can get high quality Elliptical reflectors directly from highend. Download their pdf spare parts list and look at either the trackspot, trackspot 2 or technobeam units. They all use the same lamp (MSD 250 w/ the same reflectors running about $25.00 each).
Add a dcx or pcx condenser at your set.
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Add a dcx or pcx condenser at your set.
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www.diybuildergroup.com
soon
nmd, the most common lamp used is the phillips msd 250/2
You'll find them in every nite club across the us.
BTW... highend also has technical drawing of some of their units that should help people with smaller lcd's come up new light engines.
You'll find them in every nite club across the us.
BTW... highend also has technical drawing of some of their units that should help people with smaller lcd's come up new light engines.
Trying to tell me somthing new? lol
Theres nothing wrong with my light engine now, its all sorted, ill fool with an eliptical reflector another day on a bigger model cos thats what it will take, SIZE! lol, where u been? havnt seen u around for a while.
Trev
I've been working non-stop! 🙂 I also had those dcx lenses I was telling you about custom made out of better glass after the original testing. Much better.
The Elliptical reflectors in those units are VERY SMALL and would fit right into your enclosure. They dont even cover the entire lamp and sit in the palm of your hand.
The Elliptical reflectors in those units are VERY SMALL and would fit right into your enclosure. They dont even cover the entire lamp and sit in the palm of your hand.
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