I wish I could say Isaac. My plan is to start with the lenses coming with the OHP. If you want a triplet lense you could try
http://www.diyprojectorcompany.com
Their forums are kinda where I have settled for advice, seem to be the lively ones. i know that they as a company supply parts.
Is it a PC or is it interior design?
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Thats an incredible piece of work, very impressed. I hadn't planned on anything that complex, partly because I dont think I could build anything that complex, partly because I dont know anyone else who would do it for free!
In the pictures the image looks a little dark in the corners, is this noticible in real life?
In the pictures the image looks a little dark in the corners, is this noticible in real life?
hmm i don't know anyone who'd do it for free either, i think i'm just a bit insane 
yeah unfortunately there's a lot of falloff in the corners, it's noticeable in real life but not quite to the extent of the pictures. i'm 99% sure this is caused by the over-elegance of my over-complicated design causing the parts to be further away from each other than they should be, hence allowing light to escape where it shouldn't.
still rocks playing gt4 on such a big screen though
yeah unfortunately there's a lot of falloff in the corners, it's noticeable in real life but not quite to the extent of the pictures. i'm 99% sure this is caused by the over-elegance of my over-complicated design causing the parts to be further away from each other than they should be, hence allowing light to escape where it shouldn't.
still rocks playing gt4 on such a big screen though
Have you installed a reflector around the bulb?
The other thing I could suggest, (and only through reading plenty of threads on the subject, not through personal experiance) would be to try moving the fresnell on the bulb side back and forwards.
Other than that post up on the forum I supplied the url to couple of posts back and see if they can offer some suggestions.
And yeah, it was GT4 I am looking forward to playing. UNfortunately I wont get mine done for a few months
Of yes and watching the football!
The other thing I could suggest, (and only through reading plenty of threads on the subject, not through personal experiance) would be to try moving the fresnell on the bulb side back and forwards.
Other than that post up on the forum I supplied the url to couple of posts back and see if they can offer some suggestions.
And yeah, it was GT4 I am looking forward to playing. UNfortunately I wont get mine done for a few months
Of yes and watching the football!
no... no reflector around the bulb in that design. i bought some (napkin holders from IKEA!) (i have no idea how they'd function as napkin holders though) but the bulb i'm using at the moment is physically too large to be able to use the reflector.
the position of the fresnels (and everything else apart from the projection lens) was pretty much fixed to the range i designed into it 3 months before i started testing, so unfortunately i couldn't try any small adjustments. i think this coming easter break i might try making a much simpler version, perhaps even having the parts stand separately so i can find the optimum part-to-part distance.
the position of the fresnels (and everything else apart from the projection lens) was pretty much fixed to the range i designed into it 3 months before i started testing, so unfortunately i couldn't try any small adjustments. i think this coming easter break i might try making a much simpler version, perhaps even having the parts stand separately so i can find the optimum part-to-part distance.
I would go with the reflector option first. the ones I have seen are larger bowls, with various bits cut out (Most I see use the lumenlabs bulbs so need this)
Other sources of reflectors I can think of.
Small stainless steel balti dishes
Egg poaching dishes
Thin alu sheet could be fashioned... Crude but easy.
Or how about using a ball, some plaster and heat resistant reflective paint?
Cut up steel ball cocks (just because it sounds rude)
Alu disposable pie dishes (crude but easy to shape etc)
As you can perhaps tell, I am currently looking at any shiny object I see in the shops with this in mind. I'll bet a trip to any decent sized hardware/cookware shop will give you something.
I even found instructions on the web on how to silver plate metal dishes to improve their performance.
Try the cheapest first, ie the disposable pie dish. It will give you an idea if this is the problem, then you can refine the reflector design when you find something more suitable.
Other sources of reflectors I can think of.
Small stainless steel balti dishes
Egg poaching dishes
Thin alu sheet could be fashioned... Crude but easy.
Or how about using a ball, some plaster and heat resistant reflective paint?
Cut up steel ball cocks (just because it sounds rude)
Alu disposable pie dishes (crude but easy to shape etc)
As you can perhaps tell, I am currently looking at any shiny object I see in the shops with this in mind. I'll bet a trip to any decent sized hardware/cookware shop will give you something.
I even found instructions on the web on how to silver plate metal dishes to improve their performance.
Try the cheapest first, ie the disposable pie dish. It will give you an idea if this is the problem, then you can refine the reflector design when you find something more suitable.
interesting suggestions. i remember myself keeping an eye out for anything shiny, round and concave everytime i went to the shops... heheh my gf wondered why i was so interested in saucepan lids etc.
here's a pic of the ikea napkin holders, they're smooth and chrome and perfectly spherical and quite inexpensive - can't ask for much more really!
here's a pic of the ikea napkin holders, they're smooth and chrome and perfectly spherical and quite inexpensive - can't ask for much more really!
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peteamer
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Damned interesting stuff so far Gentlemen... I'm listening in the corner and making notes (Lots of..)... 
Chylld, if you don't turn this into a full and proper thread in it's own right... I'll... I'll... err ... well just wait and see that's all...
And if you don't follow up with your experiences Mr. justblair... Well, you'll be in just as much trouble,... you'll see!!!...
As for the darkening of edges, it's called Vignetting... All lenses suffer from it.
Solution #1/ Make the lense to a much higher(/expensive) standard and the results can become invisible (depending on situation/noticability)...
Solution #2/ Only use the 'inner' portion of the lens where the problem is much less noticable...
I realise that this doesn't help much (and isn't complete in solutions), but it may help point you in the 'right' direction...
Pete
(P.S. Just sit back and watch the Johnny Wikipedia (For it is 'The Truth, The Whole Truth and Nothing but The Truth ) boys come up with quotes to prove me wrong...
)
Chylld, if you don't turn this into a full and proper thread in it's own right... I'll... I'll... err ... well just wait and see that's all...
And if you don't follow up with your experiences Mr. justblair... Well, you'll be in just as much trouble,... you'll see!!!...
As for the darkening of edges, it's called Vignetting... All lenses suffer from it.
Solution #1/ Make the lense to a much higher(/expensive) standard and the results can become invisible (depending on situation/noticability)...
Solution #2/ Only use the 'inner' portion of the lens where the problem is much less noticable...
I realise that this doesn't help much (and isn't complete in solutions), but it may help point you in the 'right' direction...
Pete
(P.S. Just sit back and watch the Johnny Wikipedia (For it is 'The Truth, The Whole Truth and Nothing but The Truth ) boys come up with quotes to prove me wrong...
)justblair:
that panel sounds quite nice. i think given your supposed destruction of a 15" lcd panel in the past, an 8" should be much easier to handle also, as peteamer points out, it'll let you stay away from the edges of your lenses and so you'll get a better image.
another good thing about projector panels (as opposed to generic lcd monitor panels) is that they come with RCA inputs, which means you don't need to have a separate TV tuner board to convert RCA -> VGA (like i did).
peteamer:
i'll make a proper thread for it when i think it's ready the thing i posted pics of was my first prototype, and tbh i'm just glad it works. now that i have a better idea of what goes where and why, the next version should be much better
vignetting is most probably a significant factor for my dark corners... however i maintain that it's simply my design that's mainly at fault here; the collector fresnel is simply at too steep an angle compared to the lcd panel. i needed this for keystone correction, but hopefully i can find another way in my upcoming 'component' build where i can find a compromise between keystone and image clarity.
that panel sounds quite nice. i think given your supposed destruction of a 15" lcd panel in the past, an 8" should be much easier to handle
also, as peteamer points out, it'll let you stay away from the edges of your lenses and so you'll get a better image.another good thing about projector panels (as opposed to generic lcd monitor panels) is that they come with RCA inputs, which means you don't need to have a separate TV tuner board to convert RCA -> VGA (like i did).
peteamer:
i'll make a proper thread for it when i think it's ready
the thing i posted pics of was my first prototype, and tbh i'm just glad it works. now that i have a better idea of what goes where and why, the next version should be much better vignetting is most probably a significant factor for my dark corners... however i maintain that it's simply my design that's mainly at fault here; the collector fresnel is simply at too steep an angle compared to the lcd panel. i needed this for keystone correction, but hopefully i can find another way in my upcoming 'component' build where i can find a compromise between keystone and image clarity.
I am not scared of tearing down another LCD panel, I dont think that I would make the same mistake again. My biggest error was in tearing down the wrong panel. It was the one in the photos in this thread. Needed a FFC cable basicly. Playing around with it I damaged the flat cables. I will in the future buy a 15'. The ezshow though was a cheap and chearful planel to experiment with. If I cock it up I wont be crying too much.chylld wrote:justblair:
that panel sounds quite nice. i think given your supposed destruction of a 15" lcd panel in the past, an 8" should be much easier to handle
another good thing about projector panels (as opposed to generic lcd monitor panels) is that they come with RCA inputs, which means you don't need to have a separate TV tuner board to convert RCA -> VGA (like i did).
peteamer:
i'll make a proper thread for it when i think it's ready
vignetting is most probably a significant factor for my dark corners... however i maintain that it's simply my design that's mainly at fault here; the collector fresnel is simply at too steep an angle compared to the lcd panel. i needed this for keystone correction, but hopefully i can find another way in my upcoming 'component' build where i can find a compromise between keystone and image clarity.
Well, i guess it had to happen sooner or later. yesterday i took apart my prototype projector design (of which pics are posted above) and made a quick-and-easy setup that allowed me to position each of the parts individually and set the angle etc. so that i could get measurements for my next prototype. took ages to take the first design apart, was extremely careful from start to beginning, but upon firing up the lcd panel for testing late last night, all i got was a zebra pattern. bugger.
i checked all the connections with a multimeter, everything was fine. i traced the problem to the lcd panel control board (not the one directly attached to the lcd panel) and realised i probably damaged it pulling it off its mdf panel, using force to overcome the double-stick foam tape i used to hold it there.
this is quite a setback, as obviously i didn't get the measurements i wanted. however, one small victory was that i managed to wrap things up on schedule, which is something i couldn't say of the making of the original prototype
the objective of the 2nd prototype was a 'more safe' version that gave me better image quality at the cost of any adjustment features, i.e. a fixed design commonly seen on diy projector forums. however, given that unplanned additional cost will now be involved, i can't justify going ahead with it since a simple design, even though it will probably work well, will not be of any use apart from providing me with a nice projection; my first design was ambitious enough to actually make new ground wrt patenting and the diy projector playing field in general.
given that i've only just started full-time employment, i don't have much money and time to play with so for now, at least, it looks like i'll be looking into a different venture time to invent.
i checked all the connections with a multimeter, everything was fine. i traced the problem to the lcd panel control board (not the one directly attached to the lcd panel) and realised i probably damaged it pulling it off its mdf panel, using force to overcome the double-stick foam tape i used to hold it there.
this is quite a setback, as obviously i didn't get the measurements i wanted. however, one small victory was that i managed to wrap things up on schedule, which is something i couldn't say of the making of the original prototype
the objective of the 2nd prototype was a 'more safe' version that gave me better image quality at the cost of any adjustment features, i.e. a fixed design commonly seen on diy projector forums. however, given that unplanned additional cost will now be involved, i can't justify going ahead with it since a simple design, even though it will probably work well, will not be of any use apart from providing me with a nice projection; my first design was ambitious enough to actually make new ground wrt patenting and the diy projector playing field in general.
given that i've only just started full-time employment, i don't have much money and time to play with so for now, at least, it looks like i'll be looking into a different venture
time to invent.Well to share the pain.
Got the ezshow panel on Fri. Getting a good quality image but the brightness isn't really there. The projector is using a 650w halogen bulb. Looks like I am going to have to look into ways of making it brighter. Thinking about adding a lense to the bulb to direct the light into just the panel. I guess I am wasting a lot of the light the bulb is creating. It is a 13500 lumens rated bulb, but I am guessing I am getting a small fraction of that at the screen. Dont want to start building a boxed projector just yet. Have not finished my passive htpc build yet.
Getting a fair bit of shearing as well playing playstation games. Pro evolultion looks and plays great, Wipeout is proving too fast for it. Playing DVD's thorugh the PS2 is blighted by the same effect. Think though this is not a problem on the panel, rather the conversion from pal to vga. Not getting the same shearing watching movies on the PC.
In short, a bit of a disapointing first result... Though certainly opportunties for improvement available.
Got the ezshow panel on Fri. Getting a good quality image but the brightness isn't really there. The projector is using a 650w halogen bulb. Looks like I am going to have to look into ways of making it brighter. Thinking about adding a lense to the bulb to direct the light into just the panel. I guess I am wasting a lot of the light the bulb is creating. It is a 13500 lumens rated bulb, but I am guessing I am getting a small fraction of that at the screen. Dont want to start building a boxed projector just yet. Have not finished my passive htpc build yet.
Getting a fair bit of shearing as well playing playstation games. Pro evolultion looks and plays great, Wipeout is proving too fast for it. Playing DVD's thorugh the PS2 is blighted by the same effect. Think though this is not a problem on the panel, rather the conversion from pal to vga. Not getting the same shearing watching movies on the PC.
In short, a bit of a disapointing first result... Though certainly opportunties for improvement available.
ahh well... it's all an experience it isn't exactly the easiest project to get right the first time around!
perhaps your brightness problem isn't with the bulb - it might be with the projection lens. a lot of overhead projectors use single or double lens arrangements, however for diy projectors a triplet lens gives the best result. (although some overheads come with triplets... maybe yours?)
it isn't exactly the easiest project to get right the first time around!perhaps your brightness problem isn't with the bulb - it might be with the projection lens. a lot of overhead projectors use single or double lens arrangements, however for diy projectors a triplet lens gives the best result. (although some overheads come with triplets... maybe yours?)
The OHP has a double lense arangement on it (and a pretty good one it seems, very little distortion.)
I think that the main problem is that the OHP is designed to display from a wider and taller source. The projection panel is only 8'. A lot of the light being produced by the bulb is simply being blanked out by the surrounding panel. Not a very efficient setup.
If I can narrow down the beam from the bulb to the fresnel set, I can get concentrate the available lumens into the 8' panel. I am guessing that I am loosing half of the light in this part of the light path alone. Thats before the LCD takes its toll.
Not sure wether to try this within the existing OHP or to wait till I build the projector. The noise of the current setup is unbelieveable. There is no way I can tolerate it for very long. At least when I build my own I can use quieter fans, more efficient airflow paths etc.
But I really need to finish my current project before I get carried away. This one has the potential to take up a lot of time and energy.
I think that the main problem is that the OHP is designed to display from a wider and taller source. The projection panel is only 8'. A lot of the light being produced by the bulb is simply being blanked out by the surrounding panel. Not a very efficient setup.
If I can narrow down the beam from the bulb to the fresnel set, I can get concentrate the available lumens into the 8' panel. I am guessing that I am loosing half of the light in this part of the light path alone. Thats before the LCD takes its toll.
Not sure wether to try this within the existing OHP or to wait till I build the projector. The noise of the current setup is unbelieveable. There is no way I can tolerate it for very long. At least when I build my own I can use quieter fans, more efficient airflow paths etc.
But I really need to finish my current project before I get carried away. This one has the potential to take up a lot of time and energy.