Henry Braithwai said:
That's BS we are reading on these forums too much these days.
The LCD *is* a very complicated optical device including polarizing filters, color filters and actual twisted neumatics TFT's, transistors which twist the lights polarization angle letting more or less light through the front and back polarizers.
mhelin said:
Yes, of course the LCD HAS optical devices IN it in order to work, and you could of course use it as a complec color filter or such, but we are NOT doing that. LCD is an object that has an image on it, just like a dia for example. The LCD itself is NOT an optical device when used in a projection setup. The lcd is the real object and the image on the wall is the fake object on the other side of the lens. That is very very very basic physics. I think that basics are something that is good to know and understand before trying to understand and develope anything else concerning projecting and optics.
Regards
HB
Henry Braithwai said:
I think you're wrong in this case. If the lcd were the 'real' object we would be reflecting light off of it to make our projection. Instead we pass light through the lcd, and the light that gets projected is being modulated by the panel itself. We treat the lcd as a 'real' object meaning we place it at the focus of our projection optics, but the fact that light travels through the panel and the light is controlled by the panel itself makes the lcd an optical component. It's a semantic argument however...
~cheers
brainchild said:
Yes, that is doable. You know it as well as I. The main problem of that kind of system is the fact that the lcd is transparent and designed to be backlit, thus the illumination of the screen is easier and much more efficient when illuminated from the opposite side of the viewing point/lens.
Well, this is a guess but I am pretty (almost 100%) sure that you cannot "modulate" normal incoherent light like that, you can filter it, and change a color of a light beam or such but the light is not in any kind of a organized and focused pattern before or after the lcd. If it would, you would not need the projection lens after the lcd. With lasers you could do that, with a kind of a laser scanning system with really really sharp red, green and blue laser beams scanning the whole screen you'd get the result where you would not need the projection lens, because the laser beams would be modulated with the pixels on the lcd.
HB
optics
modulate = light is on, off or somewhere in between
optics
\Op"tics\, n. [Cf. F. optique, L. optice, Gr. ? (sc. ?). See Optic.] That branch of physical science which treats of the nature and properties of light, the laws of its modification by opaque and transparent bodies, and the phenomena of vision.
modulate = light is on, off or somewhere in between
optics
\Op"tics\, n. [Cf. F. optique, L. optice, Gr. ? (sc. ?). See Optic.] That branch of physical science which treats of the nature and properties of light, the laws of its modification by opaque and transparent bodies, and the phenomena of vision.
Ballasts
HI guys...
I am selling 2 new ballast kits...
1) Holophane 400W metal halide ballast
2) Advance 250W metal halide ballast
they are both still in the box...
If you need any one of these, please email me at ikutuyev@sbcglobal.net
thank you🙂
HI guys...
I am selling 2 new ballast kits...
1) Holophane 400W metal halide ballast
2) Advance 250W metal halide ballast
they are both still in the box...
If you need any one of these, please email me at ikutuyev@sbcglobal.net
thank you🙂
If a BenQ measures 15" diagonally, what are the "real" measurements once stripped? Width and height and Depth?
I'm building my enclosure before the BenQ is delivered.
Tom
I'm building my enclosure before the BenQ is delivered.
Tom
The measurements of active screen area will not change once stripped. If it's labeled as 12x9" active area... that is the actual size of the LCD panel plus about 1/16 of a inch for the outter rim. It would be wise to wait for the LCD before making your mounts. Because besides the actual LCD size you may have to make changes when mounting the PCB and power supply that connects to it.
Prjctr_Builder
Did you ever work out the problems with that 508mm fl lens that you bought? I used the caclulator and that's exactly the lens that I need also.
You said it makes the right size image, but the corners were messed up. Messed up how? Did you ever play around with it and get the corners right?
tmitch007
Did you ever work out the problems with that 508mm fl lens that you bought? I used the caclulator and that's exactly the lens that I need also.
You said it makes the right size image, but the corners were messed up. Messed up how? Did you ever play around with it and get the corners right?
tmitch007
I've been reading this site for the past week and I'm looking at trying to build my own projector sometime. Right now I'm looking around for parts, but I have a question:
I was wondering if anyone has tried a headlight reflector from a car or other vehicle as a reflector for a Metal Halide or other bulb. Anyone think it could work?
Thanks 🙂
I was wondering if anyone has tried a headlight reflector from a car or other vehicle as a reflector for a Metal Halide or other bulb. Anyone think it could work?
Thanks 🙂
My Diy Videopjector
Hello
I m sorry, i m french and my english isn't very good.
Here is our web adress http://allinbox.free.fr
We are a small french team and we work on the same project.
Have a nice day
Hello
I m sorry, i m french and my english isn't very good.
Here is our web adress http://allinbox.free.fr
We are a small french team and we work on the same project.
Have a nice day
Re: Prjctr_Builder
A while back, I found an excellent explanation of how LCD's work at http://www.howstuffworks.com/lcd.htm. I HIGHLY recommend reading through it - it's written in such a way that it appeals to people with all levels of current understanding about LCD technology.
I must admit that I didn't look back to ready about the 508mm lens that you're talking about, but I'm almost certain that these problems are because this is a single lens instead of a doublet or triplet assembly. Single lenses are simply not going to cut it for video projection - they're made for focusing near-point-sources, which our LCD panels are certainly not. You really need a doublet or ideally a triplet lens to project good video. Of course I sell them on my website, but feel free to look for them elsewhere - I didn't leave this comment to try and make a buck.
Okay now I'm gonna try to make a buck (jk). I've got a pretty good collection of parts on my website at www.diylabs.org/projector/ , but you can find various parts elsewhere. The two advantages that I think are useful about purchasing from DIY Labs is that you can save money on shipping if you're going to purchase more than a couple of items by emailing me with your order instead of ordering individual parts from multiple sources, and also you can save money because many of the parts that us DIYers need are often very expensive if you purchase from another vender - I sell my parts very close to "at cost" ... I make no money at all on some of the parts I sell - especially during sales.
Even if you don't want to buy from me, feel free to email me if you need help finding a part - I've got a pretty good list of places to get certain parts.
I have thought about doing this, but the refelctor in the headlamp assembly that I have is ceramic, so it would surely crack if I tried to drill it for use with a double-ended metal halide. There are small bi-pin metal halides that look very much like a halogen auto lamp, but they are too low power/output in my opinion. The main problem with using car reflectors is that they are too big ... a good reflector would be about 3" in diameter or less - roughly smaller than the projection lens you'll be using. Another good way to boost output, regardless of the reflector you're using, is to add a condenser lens. If you go with the condenser lens that I carry, then this is a really inexpensive upgrade, too. One last thing I'd like to add is that I think people are putting too much emphasis on the exact shape of the reflector. Yes - there is an ideal shape and size for the reflector, but perfect reflectors don't exist and really good ones are usually very expensive. Most people who have tried my $8 soup ladle reflector find that it gives noticeable increase in light output. I've found companies that will manufacture better reflectors, but usually at a cost of around $100 per reflector! I'll stick with the soup ladle! On the other hand, it would be awesome if someone could figure out a different inexpensive alternative that worked as well - making those reflectors is a pain sometimes!
As a side note, I hope that everyone knows that I keep mentioning my parts and services in an attempt to help, not to profit. I like profit just as much as anyone else, but that's not my main purpose with my website. If anyone ever emails me wondering if there are alternate places to get parts, I'll be very open with advice about where else you can get certain parts, but typically I believe that I have the best prices online because I don't mark up my prices any more than I have to in order to stay in business. In fact, you benefit from most of the markup in the form of frequently updated FREE information on the website. The rest of the money (which really is very little) I use to try out new ideas and report on them so that other people don't have to waste their money trying something that doesn't work.
Hopefully everyone had a Happy Thanksgiving! If anyone needs anything from me, please email me at diylabs@hotmail.com since I don't visit the forums on a regular basis - too much to do and so little time!
mhelin said:
A while back, I found an excellent explanation of how LCD's work at http://www.howstuffworks.com/lcd.htm. I HIGHLY recommend reading through it - it's written in such a way that it appeals to people with all levels of current understanding about LCD technology.
tmitch007 said:
I must admit that I didn't look back to ready about the 508mm lens that you're talking about, but I'm almost certain that these problems are because this is a single lens instead of a doublet or triplet assembly. Single lenses are simply not going to cut it for video projection - they're made for focusing near-point-sources, which our LCD panels are certainly not. You really need a doublet or ideally a triplet lens to project good video. Of course I sell them on my website, but feel free to look for them elsewhere - I didn't leave this comment to try and make a buck.
forestsoul said:
Okay now I'm gonna try to make a buck (jk). I've got a pretty good collection of parts on my website at www.diylabs.org/projector/ , but you can find various parts elsewhere. The two advantages that I think are useful about purchasing from DIY Labs is that you can save money on shipping if you're going to purchase more than a couple of items by emailing me with your order instead of ordering individual parts from multiple sources, and also you can save money because many of the parts that us DIYers need are often very expensive if you purchase from another vender - I sell my parts very close to "at cost" ... I make no money at all on some of the parts I sell - especially during sales.
Even if you don't want to buy from me, feel free to email me if you need help finding a part - I've got a pretty good list of places to get certain parts.
forestsoul said:
I have thought about doing this, but the refelctor in the headlamp assembly that I have is ceramic, so it would surely crack if I tried to drill it for use with a double-ended metal halide. There are small bi-pin metal halides that look very much like a halogen auto lamp, but they are too low power/output in my opinion. The main problem with using car reflectors is that they are too big ... a good reflector would be about 3" in diameter or less - roughly smaller than the projection lens you'll be using. Another good way to boost output, regardless of the reflector you're using, is to add a condenser lens. If you go with the condenser lens that I carry, then this is a really inexpensive upgrade, too. One last thing I'd like to add is that I think people are putting too much emphasis on the exact shape of the reflector. Yes - there is an ideal shape and size for the reflector, but perfect reflectors don't exist and really good ones are usually very expensive. Most people who have tried my $8 soup ladle reflector find that it gives noticeable increase in light output. I've found companies that will manufacture better reflectors, but usually at a cost of around $100 per reflector! I'll stick with the soup ladle! On the other hand, it would be awesome if someone could figure out a different inexpensive alternative that worked as well - making those reflectors is a pain sometimes!
As a side note, I hope that everyone knows that I keep mentioning my parts and services in an attempt to help, not to profit. I like profit just as much as anyone else, but that's not my main purpose with my website. If anyone ever emails me wondering if there are alternate places to get parts, I'll be very open with advice about where else you can get certain parts, but typically I believe that I have the best prices online because I don't mark up my prices any more than I have to in order to stay in business. In fact, you benefit from most of the markup in the form of frequently updated FREE information on the website. The rest of the money (which really is very little) I use to try out new ideas and report on them so that other people don't have to waste their money trying something that doesn't work.
Hopefully everyone had a Happy Thanksgiving! If anyone needs anything from me, please email me at diylabs@hotmail.com since I don't visit the forums on a regular basis - too much to do and so little time!
I have tried a headlight reflector, actually it was an extralight. But it was the most stupid thing I have ever done, it was expensive too. As a reflector for parallel rays it works very good, but for a 15" TFT it´s useless, as you can see it has a big hole in the middle where you place the bulb, but if you want the light to spread from the reflector to fit a 15" TFT you have to move the bulb a little bit backwards in the reflector, when you do that the rays that should be reflecting straight ahead comes in the hole, and the result will be a circle of light on the TFT. An other thing is when you use it with a halogen bulb, you get a very very hot spot that destroys your tft in a second.
Attachments
Usefulness of that reflector
Actually I think that a condenser lens would probably fix your problem with the hotspot ring in the middle. You could additionally try to use fresnel splitting, which also does a terrific job of evening out light. Since I don't know for sure whether a condenser lens would fix your problem or not, I'd be willing to send it to you free of charge as long as you pick up the shipping expenses. It would be great if you could try out the condenser lens and let us all know if it fixed your problem. I don't know for sure how large that reflector is or how tall your lamp is, so there is a change that you couldn't get the condenser lens close enough to the lamp to competely eliminate the hotspot, but I'm willing to eat the cost of the condenser lens in order to find out. Let me know if you are interested (emailing me at diylabs@hotmail.com is best).
Actually I think that a condenser lens would probably fix your problem with the hotspot ring in the middle. You could additionally try to use fresnel splitting, which also does a terrific job of evening out light. Since I don't know for sure whether a condenser lens would fix your problem or not, I'd be willing to send it to you free of charge as long as you pick up the shipping expenses. It would be great if you could try out the condenser lens and let us all know if it fixed your problem. I don't know for sure how large that reflector is or how tall your lamp is, so there is a change that you couldn't get the condenser lens close enough to the lamp to competely eliminate the hotspot, but I'm willing to eat the cost of the condenser lens in order to find out. Let me know if you are interested (emailing me at diylabs@hotmail.com is best).
diylabs
heya allan, im interested in trying out your condenser for different aplications for free, ive got 12 different types of condensers here i could maybe make u a reconmedation on it if u get them custom made and what changes to make to the actual lens, (if there was a problem with it) now if your interested email me at ace3000_1@hotmail.com
Trev
heya allan, im interested in trying out your condenser for different aplications for free, ive got 12 different types of condensers here i could maybe make u a reconmedation on it if u get them custom made and what changes to make to the actual lens, (if there was a problem with it) now if your interested email me at ace3000_1@hotmail.com
Trev
Re: My Diy Videopjector
There are some nice pics of a projector build with aluminium.
Some technical improvement and this design would really rock!
allinside said:
There are some nice pics of a projector build with aluminium.
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.
Some technical improvement and this design would really rock!
Re: aluminum projector
that's a really cool lookin' projector. How does your lens focus, or is it mostly a fixed-lens system? How did you construct your projector (did you use someone else's design or go for it on your own). Thanks!
that's a really cool lookin' projector. How does your lens focus, or is it mostly a fixed-lens system? How did you construct your projector (did you use someone else's design or go for it on your own). Thanks!
I found those pics on the french website mentioned in the quote above. My own projector is still in the first stage of construction - in my mind... 🙂
Does my english suck that hard? 🙄
Here http://allinbox.free.fr/phial/phial.htm and here http://perso.wanadoo.fr/videoprojecteur/ 😉
I recommend you to run that website through bablefish or something if you can't read french. I can.
Here http://allinbox.free.fr/phial/phial.htm and here http://perso.wanadoo.fr/videoprojecteur/ 😉
I recommend you to run that website through bablefish or something if you can't read french. I can.