Hey Mario007,
Was your condenser really thick like this one:
http://www.surplusshed.com/pages/Lenses.html
Item L2087
?
J
Was your condenser really thick like this one:
http://www.surplusshed.com/pages/Lenses.html
Item L2087
?
J
Mitch
With my design it is not possible to get a large image at a close
distance. This is because my LCD panel is 10" Diagonal.
But if you can get a bigger Plano convex lens, say 12" then your in luck. I also tried two page magnifiers for the end lens (panel to screen, and it wasnt to bad (better with glass though). If you can get 2 glass frenel lens's with the lenticular line being fine (more lines per inch) the you should be good to go. Make sure that the
lenticular/ fresnel's are perfectly in line.
My MH bulb is in a metal box, and the reflector or any other shinny
stuff does not heat up. Therefore my job was to get the heat from
the bulb itself out. The only thing that I am doing is to have those
12Volt computer case fans (three of them) blowing air into the bottom of my metal box and a hole on top for out.
The heat sink is for my ballast (it getts hot). I have 2 pieces of aluminium about 12"x12" with heat sink compound on it and bolted the ballast between the two sheets.
With my design it is not possible to get a large image at a close
distance. This is because my LCD panel is 10" Diagonal.
But if you can get a bigger Plano convex lens, say 12" then your in luck. I also tried two page magnifiers for the end lens (panel to screen, and it wasnt to bad (better with glass though). If you can get 2 glass frenel lens's with the lenticular line being fine (more lines per inch) the you should be good to go. Make sure that the
lenticular/ fresnel's are perfectly in line.
My MH bulb is in a metal box, and the reflector or any other shinny
stuff does not heat up. Therefore my job was to get the heat from
the bulb itself out. The only thing that I am doing is to have those
12Volt computer case fans (three of them) blowing air into the bottom of my metal box and a hole on top for out.
The heat sink is for my ballast (it getts hot). I have 2 pieces of aluminium about 12"x12" with heat sink compound on it and bolted the ballast between the two sheets.
Attachments
Gunawan W
The 2 lenses is to make the bright spot bigger, keep the light
square and parellel. Shorter distance.
It works great for me. I tried the reflector thing. If your using an
LCD panel use this method. Put a half curved reflector on the back
side. Make sure it is not mirror material, or it will creat another
beam or two. Use semi reflective material. I used one of those
stove pipe tubes or dryer vent ones. Something like that.
The 2 lenses is to make the bright spot bigger, keep the light
square and parellel. Shorter distance.
It works great for me. I tried the reflector thing. If your using an
LCD panel use this method. Put a half curved reflector on the back
side. Make sure it is not mirror material, or it will creat another
beam or two. Use semi reflective material. I used one of those
stove pipe tubes or dryer vent ones. Something like that.
Attachments
Redevil,
Are your two fresnal light magnifiers glass or plastic? If they are plastic, it seems that they would get to hot and melt.....maybe not. I don`t know too much about them and what they can take.
Do you have any idea if they even make a 12" PCX? I`ve looked but I have seen any.
Mitch
Are your two fresnal light magnifiers glass or plastic? If they are plastic, it seems that they would get to hot and melt.....maybe not. I don`t know too much about them and what they can take.
Do you have any idea if they even make a 12" PCX? I`ve looked but I have seen any.
Mitch
condenser
just curious if anyone is using a condenser lens other than the melles griot lens at surplusshed.
just curious if anyone is using a condenser lens other than the melles griot lens at surplusshed.
Hey,
Me again. Maybe this is old news, but check out this link. It tells you, if you know how far away you want your projector to be to the screen, which lens to get. Look carefully at step two. It also says to use an achromatic lens instead of a PCX. (those aren`t the same thing are they?)
Theres some good stuff here.
http://www.vinci.it/Nuova cartella/...l Support Quick Tips for Projector Design.htm
big link. Hope it works for ya
Me again. Maybe this is old news, but check out this link. It tells you, if you know how far away you want your projector to be to the screen, which lens to get. Look carefully at step two. It also says to use an achromatic lens instead of a PCX. (those aren`t the same thing are they?)
Theres some good stuff here.
http://www.vinci.it/Nuova cartella/...l Support Quick Tips for Projector Design.htm
big link. Hope it works for ya
Hmmm. i`m not so sure about that site. It says that if I want to set the projector 375mm (15") away from the screen, then I need a lens with a 18mm fl. Thats with a 20x magnification. Does that sound right to you guys?
Then I would need a huge projector lens to be able to see all of my 14" LCD...right? This is getting a bit more complicated.
Then I would need a huge projector lens to be able to see all of my 14" LCD...right? This is getting a bit more complicated.
Mitch
The first lens after the bulb is glass.
The 2 page magnifiers or fresnel lens are plastic. Bought them
at Staples in Canada. I think you have a Home Depo there.
My setup runs horizonal. Any extra heat developed goes straight up. They do not get hot. All the heat is traped into the metal box housing and the heat is removed by the 3 fans. My LCD panel
is always cool, not ever warm. Left it on for three days straight,
panel still cool.
As far as the lens after the LCD panel, look into lenses used
for light shows. They may be 9 or 12 inches round. If you have no luck try putting 2 plano convex lenses (4"ones) 1 or 2 inches
apart in a home made rolled tube.
The first lens after the bulb is glass.
The 2 page magnifiers or fresnel lens are plastic. Bought them
at Staples in Canada. I think you have a Home Depo there.
My setup runs horizonal. Any extra heat developed goes straight up. They do not get hot. All the heat is traped into the metal box housing and the heat is removed by the 3 fans. My LCD panel
is always cool, not ever warm. Left it on for three days straight,
panel still cool.
As far as the lens after the LCD panel, look into lenses used
for light shows. They may be 9 or 12 inches round. If you have no luck try putting 2 plano convex lenses (4"ones) 1 or 2 inches
apart in a home made rolled tube.
Thanks Redevil,
I think I may have found something that is useful. I have learned that a Double Concave lens will take single light beam and throw it out at a gazillion different directions. (Towards the LCD, of course)
So heres my plan now.
After the Metal halide bulb I will put a single glass 4-7/16" condensor lens. A few inches after that a 3-1/2" dbl concave diverging lens. This will spread all the light out to the 2 following fresnal lens. After the last fresnal lens will be my LCD.
Now heres the cool part. I am going to size my 14" 1024 x 740 resolution LCD down to a 10" with the control buttons on the front of the monitor. This makes an amazing picture.
Then I will place a 6" PCX lens with a 14" FL in front of the LCD as the projection lens.
That sounds pretty good to me if I can get that lighting design to work good. Whadaya think about that?
Mitch
I think I may have found something that is useful. I have learned that a Double Concave lens will take single light beam and throw it out at a gazillion different directions. (Towards the LCD, of course)
So heres my plan now.
After the Metal halide bulb I will put a single glass 4-7/16" condensor lens. A few inches after that a 3-1/2" dbl concave diverging lens. This will spread all the light out to the 2 following fresnal lens. After the last fresnal lens will be my LCD.
Now heres the cool part. I am going to size my 14" 1024 x 740 resolution LCD down to a 10" with the control buttons on the front of the monitor. This makes an amazing picture.
Then I will place a 6" PCX lens with a 14" FL in front of the LCD as the projection lens.
That sounds pretty good to me if I can get that lighting design to work good. Whadaya think about that?
Mitch
Way to go Mitch
I think you have seen the light.
Thats what I think my glass lens is, it curves out on both sides
and expands the light. Try it with the condenser lens.
That sounds like a good idea, but I never tried that.
Keep on trying and dont give up. Once you are done, you will be so thrilled withe the results. People will start freaking when they
see it, and will want you to make one for them. A year ago I started with the 100"TV thing, moved on to better and better.
And now to perfect.
Be sure to have the fresnel in the right order. Makes a big difference. if you forgot look back.
Keep me posted
Good Luck
Later
I think you have seen the light.
Thats what I think my glass lens is, it curves out on both sides
and expands the light. Try it with the condenser lens.
That sounds like a good idea, but I never tried that.
Keep on trying and dont give up. Once you are done, you will be so thrilled withe the results. People will start freaking when they
see it, and will want you to make one for them. A year ago I started with the 100"TV thing, moved on to better and better.
And now to perfect.
Be sure to have the fresnel in the right order. Makes a big difference. if you forgot look back.
Keep me posted
Good Luck
Later
Mitch do yourself a favor and go to a store and checkout all the 14 inch lcd panels. Find one that allows image resizing try it out and make the image 10". Notice the tremendous distortion. Why shrink it down? It'll also let less light through then if you had the full 14" for the image.
Mario007,
I wasn`t aware that it caused distortion when you shrunk it. If what you say is true, then that kinda suks. I know that when you shrink a regular monitor the picture remains bright and clear. However, I realize regular monitors are totally different than LCD`s.
Do you know this for a fact or is it more of a speculation...?
The reason I want to shrink the picture to 10" is so my 6" PCX will get the whole picture and it won`t be as much screen to pick up. Whereas if I leave it 14", the edges might not look so good with only a 6" PCX.
Thanks for the warning, though. I`ll make sure and check it out.
Redevil,
do you have a convex or concave dispersion lens. I think you said earlier that you had a double convex for the lens closest to your bulb. I might be mistaken.
What I found out tonight is that a double concave (both sides curve inward) does it really well. I don`t know if a convex works just the same.
But if yours works really good, then who cares, ya know?
It`ll be awhile before I start building mine cause I am in the middle of finishing out our attic where i`m going to put this thing. But after I get it finished I will definitely take pics and post them on here.
I wasn`t aware that it caused distortion when you shrunk it. If what you say is true, then that kinda suks. I know that when you shrink a regular monitor the picture remains bright and clear. However, I realize regular monitors are totally different than LCD`s.
Do you know this for a fact or is it more of a speculation...?
The reason I want to shrink the picture to 10" is so my 6" PCX will get the whole picture and it won`t be as much screen to pick up. Whereas if I leave it 14", the edges might not look so good with only a 6" PCX.
Thanks for the warning, though. I`ll make sure and check it out.
Redevil,
do you have a convex or concave dispersion lens. I think you said earlier that you had a double convex for the lens closest to your bulb. I might be mistaken.
What I found out tonight is that a double concave (both sides curve inward) does it really well. I don`t know if a convex works just the same.
But if yours works really good, then who cares, ya know?
It`ll be awhile before I start building mine cause I am in the middle of finishing out our attic where i`m going to put this thing. But after I get it finished I will definitely take pics and post them on here.
I've played with the viewsonic vg150 and it distorted a lot. Use a projection panel as those are mainly 10" panels. I have never understood why excatly you want to use only 10" that is what I'm confused about.
Like I said before. I`m afraid that if the screen is a full 14", my 6" PCX won`t pick up the full picture. Or else it might leave the edges kinda blurry since its not a big lens. See what I`m saying?
Do you think 1440 x 234 resolution would be good enough to be projected. Its one of those little 7" seat-rest LCD for cars. I`m looking more towards this anyway because of (1). They are cheaper. (2). They would be small enough for my 6"pcx. (3)My box wouldn`t have to be 19" wide. (4). I wouldn`t have to buy one of those expensive VGA to RCA adapters.
But, if this lens WILL pick up the entire picture, I would be willing to spend a bit more money to get a better picture
Do you think 1440 x 234 resolution would be good enough to be projected. Its one of those little 7" seat-rest LCD for cars. I`m looking more towards this anyway because of (1). They are cheaper. (2). They would be small enough for my 6"pcx. (3)My box wouldn`t have to be 19" wide. (4). I wouldn`t have to buy one of those expensive VGA to RCA adapters.
But, if this lens WILL pick up the entire picture, I would be willing to spend a bit more money to get a better picture
spot and condenser lens and another problem
Hi all,
Well I figured out my problem with the light bulb image being focused onto the LCd. As I suspected, it was my condenser lens. I grabbed a condenser from a 3M 9550 OHP, and popped it in my setup, and there was no lamp image. Moral of the story, make sure you get a good condenser lens.
Now, however I still can't get a bright image of my LCD screen from corner to corner. The focal point of the fresnel seems to be only about 6 inches past the LCD (measured by putting a white piece of paper in front of the LCD):
Lamp Fresnel LCD FOCAL POINt
} | || X
I thought it should be more like 12 inches past, that would make sense for an overhead projector. Because the focal point is so close to the LCD, the objective lens I have won't focus the image. When I move the objective further out, it focuses the image, but then it is dim, because a lot of the light cone is missing the objective lens. Does anyone know what is going on here? Do I have my Fresnel to close to the light source, does that matter at all? By all rights the focal point of the Fresnel should be about 12 inches, since it was from an OHP (well, 12 inches give or take).
Anyone know what is going on here?
At least I figured out the condenser lens problem
🙂
J
Hi all,
Well I figured out my problem with the light bulb image being focused onto the LCd. As I suspected, it was my condenser lens. I grabbed a condenser from a 3M 9550 OHP, and popped it in my setup, and there was no lamp image. Moral of the story, make sure you get a good condenser lens.
Now, however I still can't get a bright image of my LCD screen from corner to corner. The focal point of the fresnel seems to be only about 6 inches past the LCD (measured by putting a white piece of paper in front of the LCD):
Lamp Fresnel LCD FOCAL POINt
} | || X
I thought it should be more like 12 inches past, that would make sense for an overhead projector. Because the focal point is so close to the LCD, the objective lens I have won't focus the image. When I move the objective further out, it focuses the image, but then it is dim, because a lot of the light cone is missing the objective lens. Does anyone know what is going on here? Do I have my Fresnel to close to the light source, does that matter at all? By all rights the focal point of the Fresnel should be about 12 inches, since it was from an OHP (well, 12 inches give or take).
Anyone know what is going on here?
At least I figured out the condenser lens problem
🙂
J
Is or has anyone used tubular metal halide lamps? the type that are in industrial fixings?
I am attempting to retrofit my existing quartz-halogen OHP with something brighter and longer lasting and these tubular lamps are the only thing that will fit in between the condenser on this particular ohp.
These things are damn huge in length and give off around 40,000 lm.
One more thing, is it possible to get hold of 400 watt double ended metal halide lamps? if so, please please point me in the right direction.
cheers,
I am attempting to retrofit my existing quartz-halogen OHP with something brighter and longer lasting and these tubular lamps are the only thing that will fit in between the condenser on this particular ohp.
These things are damn huge in length and give off around 40,000 lm.
One more thing, is it possible to get hold of 400 watt double ended metal halide lamps? if so, please please point me in the right direction.
cheers,
jco9w,Mario007,
distance between lamp spark/filament to the lens (convex / positive) must be smaller than it's focal length to get dispersion effect. Bigger than fl. it's start to collimate light.
Redevil,
with your setup, there are wasted beam of light after leaving the fresnel (see attached dwg1), because it's parallel beam, not collimated beam.
You don't need distance between 2 fresnel panel, you can put it close together to get parallel beam, just place the panel at 1 focal length distance to the lamp-spark/filament. (the 2 panel now act as single panel with new focal length=half of original fl. of single panel).
With drawing 2 setup, no wasted light, because all light beam goes to the objective lens.
Mitch,
please have a look at my spreadsheet at my website, it's explaining how to calculate lens, distance etc.
Rule of thumb, you need lens with diameter 1/3 of diagonal size of the LCD panel, to get whole image to be projected.
To get your setup work as your plan, you need to know the focal length and placing distance toward the lamp of condenser lens and concave lens, please do calculation before buying lenses to avoid useless lenses afterthat.
Actually to disperse light you can use either convex or concave lens, it depends on the distance of the lens toward the lamp.
jco9w,
if your fresnel fl.=12", then if your lamp at 12" behind the fresnel, you get parallel beam, Move the lamp further away, it's start to condense until the light beam covered your objective lens.
distance between lamp spark/filament to the lens (convex / positive) must be smaller than it's focal length to get dispersion effect. Bigger than fl. it's start to collimate light.
Redevil,
with your setup, there are wasted beam of light after leaving the fresnel (see attached dwg1), because it's parallel beam, not collimated beam.
You don't need distance between 2 fresnel panel, you can put it close together to get parallel beam, just place the panel at 1 focal length distance to the lamp-spark/filament. (the 2 panel now act as single panel with new focal length=half of original fl. of single panel).
With drawing 2 setup, no wasted light, because all light beam goes to the objective lens.
Mitch,
please have a look at my spreadsheet at my website, it's explaining how to calculate lens, distance etc.
Rule of thumb, you need lens with diameter 1/3 of diagonal size of the LCD panel, to get whole image to be projected.
To get your setup work as your plan, you need to know the focal length and placing distance toward the lamp of condenser lens and concave lens, please do calculation before buying lenses to avoid useless lenses afterthat.
Actually to disperse light you can use either convex or concave lens, it depends on the distance of the lens toward the lamp.
jco9w,
if your fresnel fl.=12", then if your lamp at 12" behind the fresnel, you get parallel beam, Move the lamp further away, it's start to condense until the light beam covered your objective lens.
Attachments
Hey mitch you were wanting a 10" panel? Almost all projection panels are 10". If you want high res you can get a 1024*768 panel for about 200$ if you look hard. Projection panel is specifically designed for projection.Where as a desktop panel you can have serious problems with moving the driver board out of the way. Only thing I don't like is the contrast ratios of projection panels 150:1 where many desktop panels have twice that. Do whatever you want to do but if you read some of the posts in the first diy video projector thread you will hear some pretty bad stories of people killing their panels.
Gunawan W,
So if my Fresnel's focal length is 12 inches, do I want the lamp 12 inches from the fresnel or the condenser lens 12 inches from the fresnel?
See I am confused because I have the Marlkar setup, with the lamp inside an ellipsoidal reflector, which has the light converging at a small spot (the burning carboard test proves this), then I have a condenser lens in front of that spot. From there a circle of diffused, but bright light comes out. Now I have to put my Fresnel/LCD combo at a point where that circle (which expands as you move away from the condenser) is as big as the LCD.
The point is that I don't have too much of a choice where I put the Frensel/LCD, however the spot where the circle is just big enough happens to be at least 12 inches away, but I still get the light converging through the frensel on the other side at about 6 inches away.
I will just have to play with this once I get my condenser lens.
J
So if my Fresnel's focal length is 12 inches, do I want the lamp 12 inches from the fresnel or the condenser lens 12 inches from the fresnel?
See I am confused because I have the Marlkar setup, with the lamp inside an ellipsoidal reflector, which has the light converging at a small spot (the burning carboard test proves this), then I have a condenser lens in front of that spot. From there a circle of diffused, but bright light comes out. Now I have to put my Fresnel/LCD combo at a point where that circle (which expands as you move away from the condenser) is as big as the LCD.
The point is that I don't have too much of a choice where I put the Frensel/LCD, however the spot where the circle is just big enough happens to be at least 12 inches away, but I still get the light converging through the frensel on the other side at about 6 inches away.
I will just have to play with this once I get my condenser lens.
J
jco9w,
i don't understand your setup completely. Are you using an elliptical reflector AND a fresnel? How large is this reflector?
If it is able to generate a descending light cone, which 1. transmits complete panel and 2. has it's second focal point at the plane, where objective lens is, then you should not need a further condensor (fresnel).
If the reflector is smallel than LCD, an elliptical reflector doesn't work! Then it's better to have a spherical one, which doubles the filament brightness and as condensor(s) use the fresnel(s). You have to move then the lightsource until the light cone has it's smallest spot at objectiv's plane.
xblocker
i don't understand your setup completely. Are you using an elliptical reflector AND a fresnel? How large is this reflector?
If it is able to generate a descending light cone, which 1. transmits complete panel and 2. has it's second focal point at the plane, where objective lens is, then you should not need a further condensor (fresnel).
If the reflector is smallel than LCD, an elliptical reflector doesn't work! Then it's better to have a spherical one, which doubles the filament brightness and as condensor(s) use the fresnel(s). You have to move then the lightsource until the light cone has it's smallest spot at objectiv's plane.
xblocker