Here is the model that I thought I was showing above. You can see the fan mockup and the magnetic shield in place over where the transformer will be mounted.
If you look closely you can somewhat make out the mirror mounting mechanism. Two bars mount the mirror at four points which can be shimmed with felt washers to get the exact angle. Also the whole mount can pivot up and down in one degree of freedom to set the vertical angle of the mirror.
Since this thing is so big I am thinking of covering the large lower chamber with thin clear acrylic to make it more see through. It will be like a museum piece. The lower chamber will be sealed off from the other chambers and will vent hot air out the back near the top.
Hezz
If you look closely you can somewhat make out the mirror mounting mechanism. Two bars mount the mirror at four points which can be shimmed with felt washers to get the exact angle. Also the whole mount can pivot up and down in one degree of freedom to set the vertical angle of the mirror.
Since this thing is so big I am thinking of covering the large lower chamber with thin clear acrylic to make it more see through. It will be like a museum piece. The lower chamber will be sealed off from the other chambers and will vent hot air out the back near the top.
Hezz
Attachments
first surface mirror
Since that mirror is just part of the condensor system, I don't think using a standard second surface mirror would make any difference. And you can get a 12" by 12" mirror tile at a building supply store for about $1 US.
That would be considerably less than what you would pay for such a piece of 3/4" aluminum, not to mention the weight difference. I also think you will have a very hard time getting a piece of aluminum plate to be as optically flat and reflective as the $1 mirror tile.
The mirror tile would also have an advantage of being the same thickness as the first surface glass mirror you mentioned buying later. That would mean your geometry would not change switching between the two glass mirrors.
Since that mirror is just part of the condensor system, I don't think using a standard second surface mirror would make any difference. And you can get a 12" by 12" mirror tile at a building supply store for about $1 US.
That would be considerably less than what you would pay for such a piece of 3/4" aluminum, not to mention the weight difference. I also think you will have a very hard time getting a piece of aluminum plate to be as optically flat and reflective as the $1 mirror tile.
The mirror tile would also have an advantage of being the same thickness as the first surface glass mirror you mentioned buying later. That would mean your geometry would not change switching between the two glass mirrors.
Guy,
I always thought that a cheap mirror would be OK in the light engine but the guys that have experimented with them have always found the first surface mirrors to be far better because the regular mirrors create a small ghosting effect. The reason for this is because since the light is hitting a clear piece of plastic or glass at very close to brewsters angle a lot of light is reflected by the plastic surface itself and is slightly out of focus compared to the mirror surface.
I don't think that flatness is an issue at all and all of the highest quality mirrors ar made by hand by amateur telescope makers, granted it is a lot more work and costs more than a cheap mirror but I figure the metal will cost me about 20 - 25 USD at a specialty metals store if I can find a remnant. The machining would be expensive and would put it out of the cost ballpark except that I am machining it myself.
Anyway, I checked at my local Home Depot and they only sell mirror tiles in whole boxes and they are not big enough. I need a 13.5 x 15 inch mirror. And even if I decide not to make the machined mirror I can make a cheap homemade mirror out of a piece of thin aluminum bonded to some MDF.
After all, this is intended to be a high end project so why not go for it.
Hezz
I always thought that a cheap mirror would be OK in the light engine but the guys that have experimented with them have always found the first surface mirrors to be far better because the regular mirrors create a small ghosting effect. The reason for this is because since the light is hitting a clear piece of plastic or glass at very close to brewsters angle a lot of light is reflected by the plastic surface itself and is slightly out of focus compared to the mirror surface.
I don't think that flatness is an issue at all and all of the highest quality mirrors ar made by hand by amateur telescope makers, granted it is a lot more work and costs more than a cheap mirror but I figure the metal will cost me about 20 - 25 USD at a specialty metals store if I can find a remnant. The machining would be expensive and would put it out of the cost ballpark except that I am machining it myself.
Anyway, I checked at my local Home Depot and they only sell mirror tiles in whole boxes and they are not big enough. I need a 13.5 x 15 inch mirror. And even if I decide not to make the machined mirror I can make a cheap homemade mirror out of a piece of thin aluminum bonded to some MDF.
After all, this is intended to be a high end project so why not go for it.
Hezz
It seems that the fresenl lens that I ordered from Lumenlabs is the wrong focal length for the DIYprojectorcompany 135 mm diameter triplet.
There was some discussion on another forum about some of the Lumenlabs fresnels being the wrong size so I measured mine. Mine was one of the right ones at 790 mm FL. But it turns out that I am going to need something like a 600 mm FL fresnel. I will have to look for one or else try and use a large homemade singlet.
When I measured the lens to LCD distance of my lens it seemed to be 15.75 inches and about the same for each orientation. I tried the lens in both directions as most lenses are designed to work in one direction only. I could not detect the difference with my crude methods but perhaps I need to test this lens again to make sure I am using it in the right orientation.
Here is a sketch of the fresnel requirements for the lens with the 15.75 lens to LCD distance. I hope that it isn't too large to post.
Hezz
There was some discussion on another forum about some of the Lumenlabs fresnels being the wrong size so I measured mine. Mine was one of the right ones at 790 mm FL. But it turns out that I am going to need something like a 600 mm FL fresnel. I will have to look for one or else try and use a large homemade singlet.
When I measured the lens to LCD distance of my lens it seemed to be 15.75 inches and about the same for each orientation. I tried the lens in both directions as most lenses are designed to work in one direction only. I could not detect the difference with my crude methods but perhaps I need to test this lens again to make sure I am using it in the right orientation.
Here is a sketch of the fresnel requirements for the lens with the 15.75 lens to LCD distance. I hope that it isn't too large to post.
Hezz
Attachments
I spent most of the day testing and measuring the 135 mm diameter lens and it turns out that indeed it does focus from different distances depending on how it is turned. At a distance of about 11 feet from the wall I get the short distance of rear lens to LCD of 15.5 inches and when turned around I get a rear lens to LCD distance of 18.5 inches. At this point holding the lens by hand it was difficult to tell if there ws an imaging quality difference. Subjectively, the longer distance seemed to have a slight egde in image quality and the projected image is slightly smaller which is what I need.
I have determined that I may just be able to get by with the Lumenlabs fresnel if I use a 15.4 inch LCD instead of a 17 inch one. Based on my projector to wall distance I will have to use the 15.4 LCD because my wall space is insufficient for the 17 inch LCD and I can't move the projector any closer to the wall.
Here is an updated sketch of the lens and fresnel light cones. These focusing distances are for an approximate 11 foot lens to wall distance. The 790 mm FL fresnel will just barely fit it's light cone into the aperture of the 135 mm lens if I use a 15.4 inch LCD.
Hezz
I have determined that I may just be able to get by with the Lumenlabs fresnel if I use a 15.4 inch LCD instead of a 17 inch one. Based on my projector to wall distance I will have to use the 15.4 LCD because my wall space is insufficient for the 17 inch LCD and I can't move the projector any closer to the wall.
Here is an updated sketch of the lens and fresnel light cones. These focusing distances are for an approximate 11 foot lens to wall distance. The 790 mm FL fresnel will just barely fit it's light cone into the aperture of the 135 mm lens if I use a 15.4 inch LCD.
Hezz
Attachments
I am also going to have to increase the LCD to rear lens distance on the projector and even though this give the projector a rerally long snout it looks as if I have no choice unless I want to flip the bill of 135 USD to get a 600 mm FL fresnel from Edmonds optic. I tried searching the internet for 600 - 650 mm FL fresnels but I have had no luck so far. I am going to try to get by with this fresnel and the worst that will happen is that I will have some reduced light output.
Here's model with new lens adapter plate. I have some pictures in the works but I want to wait on those and get more of them developed at once.
I also have a design idea to enhance the light output of the light engine but I need to flesh that out a little more. I am going to have to redesign the whole reflector assembly to adapt to the 15.4 inch LCD.
Hezz
Here's model with new lens adapter plate. I have some pictures in the works but I want to wait on those and get more of them developed at once.
I also have a design idea to enhance the light output of the light engine but I need to flesh that out a little more. I am going to have to redesign the whole reflector assembly to adapt to the 15.4 inch LCD.
Hezz
Attachments
LL 650 fresnel
These are not just for replacing the ones they sent out that were made wrong. They should have these new 650 mm fl fresnels for sale as well. Definitely, check with LL before you spend so much!
Did you really measure your LL "790 mm" lens focal length? When I measured mine, I think it was actually more like 767 mm!
These are not just for replacing the ones they sent out that were made wrong. They should have these new 650 mm fl fresnels for sale as well. Definitely, check with LL before you spend so much!
Did you really measure your LL "790 mm" lens focal length? When I measured mine, I think it was actually more like 767 mm!
HEZZ:
I bought first surface mirror from Delphy Glass company.
It is 12x16 inch mirror. Price was 24.95 US$ plus shipping to Europe 14.00 US$.
I think they will cut you a custom size. You could ask them.
Their web page:
http://www.delphiglass.com/
My mirror is 2 mm thick. They sell this mirrors for use in making caleidoscopes
Cheers !
I bought first surface mirror from Delphy Glass company.
It is 12x16 inch mirror. Price was 24.95 US$ plus shipping to Europe 14.00 US$.
I think they will cut you a custom size. You could ask them.
Their web page:
http://www.delphiglass.com/
My mirror is 2 mm thick. They sell this mirrors for use in making caleidoscopes
Cheers !
Guys,
Thanks for your information and responses. I don't know if my L.L. fresnel is going to be replaced or not because it seems to have a FL close to what was advertized. I do hope that Brainchild does stock a 650 mm FL fresnel in the future as that is a much more useable size for the 135 mm lens.
Guy, I'm sure that my fresnel measurement is not exact because I did not have the setup to get a highly accurate measurement. I was mostly concerned if I had the 790 mm or not. I certainly hope my fresnel is really 767 mm as that would be a bit better.
I'm thinking it just might work with a 15.4 LCD.
I also think that I have come up with a more useful way for my light engine light recycler to work with a broader range of applications. I will post a diagram later today of how it works slightly different than the first design. It will be adaptable to most projectors that use a mirror at 45 degrees in the light engine.
Also, thanks for the first surface mirror info. If I am using a 15.4 LCD I just might be able to get by with a smaller mirror.
Hezz
Thanks for your information and responses. I don't know if my L.L. fresnel is going to be replaced or not because it seems to have a FL close to what was advertized. I do hope that Brainchild does stock a 650 mm FL fresnel in the future as that is a much more useable size for the 135 mm lens.
Guy, I'm sure that my fresnel measurement is not exact because I did not have the setup to get a highly accurate measurement. I was mostly concerned if I had the 790 mm or not. I certainly hope my fresnel is really 767 mm as that would be a bit better.
I'm thinking it just might work with a 15.4 LCD.
I also think that I have come up with a more useful way for my light engine light recycler to work with a broader range of applications. I will post a diagram later today of how it works slightly different than the first design. It will be adaptable to most projectors that use a mirror at 45 degrees in the light engine.
Also, thanks for the first surface mirror info. If I am using a 15.4 LCD I just might be able to get by with a smaller mirror.
Hezz
precise focal length measurement
>I did not have the setup to get a highly accurate measurement
Yes, you do! All you need is a yard stick or tape measure and the sun to measure very precisely.
You can do it indoors with a distant light bulb, using the formula:
1/fl = 1/bulb-to-lens + 1/lens-to-image
But if you use the sun as the "bulb", then 1/bulb-to-lens ~ zero. So the focal length is just the distnace from the lens to the smallest image you can make of the sun on the ground.
BTW, I'm using the LL 767 mm fl "790" in my 15" projector, but I am also using a 570 mm long-throw lens to fit the image and projector placement to my media room. I cut the fresnels extra-large so I can increase the distance between them and the LCD to tweak the location of the light cone into the projection lens.
>I did not have the setup to get a highly accurate measurement
Yes, you do! All you need is a yard stick or tape measure and the sun to measure very precisely.
You can do it indoors with a distant light bulb, using the formula:
1/fl = 1/bulb-to-lens + 1/lens-to-image
But if you use the sun as the "bulb", then 1/bulb-to-lens ~ zero. So the focal length is just the distnace from the lens to the smallest image you can make of the sun on the ground.
BTW, I'm using the LL 767 mm fl "790" in my 15" projector, but I am also using a 570 mm long-throw lens to fit the image and projector placement to my media room. I cut the fresnels extra-large so I can increase the distance between them and the LCD to tweak the location of the light cone into the projection lens.
Guy,
I used the sun method as you describe but it was a very bright day and I could not hold the fresnel in place for more than about 5 seconds before it would start a fire so I had to get someone to measure for me. I sacrificed a piece of old wood. I think that I was accurate enough for what I was looking for.
Great find on a 570 mm FL lens. I would rather have a 500 mm myself but I will be able to make the 450 mm lens work. Did you find a large format photography lens somewhere.
It sounds like that my lens is really a 767 which is good. Because it is probably the same lens as yours.
Also, I finally found a transreflective polarizer from 3M that would make my light engine more flexible. The product information kit with samples is 1200 USD so scrape that idea unless I can get one small peice somewhere.
I need one reflective polarizer and one transreflective polarizer to make the light engine work easily in either orientation.
Hezz
I used the sun method as you describe but it was a very bright day and I could not hold the fresnel in place for more than about 5 seconds before it would start a fire so I had to get someone to measure for me. I sacrificed a piece of old wood. I think that I was accurate enough for what I was looking for.
Great find on a 570 mm FL lens. I would rather have a 500 mm myself but I will be able to make the 450 mm lens work. Did you find a large format photography lens somewhere.
It sounds like that my lens is really a 767 which is good. Because it is probably the same lens as yours.
Also, I finally found a transreflective polarizer from 3M that would make my light engine more flexible. The product information kit with samples is 1200 USD so scrape that idea unless I can get one small peice somewhere.
I need one reflective polarizer and one transreflective polarizer to make the light engine work easily in either orientation.
Hezz
570 mm fl lens
>Did you find a large format photography lens somewhere?
I wish! There is a 6" diameter WWII ariel photography lens I would love to get ahold of, but they are difficult to find.
I am experimenting with a number of different lenses with focal lengths around 570 mm. I have a DIY achromat, a DIY symmetrical duplet, a DIY front meniscus, and a telescope objective. So far the DIY achromat lens works the best, but that is probably just because it is the largest diameter and my condensor system needs some tuning. The screen image is watchable, but not as sharp around the edges as it should be.
I also have a very large 571 mm fl positive meniscus lens on its way, so that may be an improvement.
BTW: You can focus the sun's image on a BRICK or a paving stone. No need to start a fire!
>Did you find a large format photography lens somewhere?
I wish! There is a 6" diameter WWII ariel photography lens I would love to get ahold of, but they are difficult to find.
I am experimenting with a number of different lenses with focal lengths around 570 mm. I have a DIY achromat, a DIY symmetrical duplet, a DIY front meniscus, and a telescope objective. So far the DIY achromat lens works the best, but that is probably just because it is the largest diameter and my condensor system needs some tuning. The screen image is watchable, but not as sharp around the edges as it should be.
I also have a very large 571 mm fl positive meniscus lens on its way, so that may be an improvement.
BTW: You can focus the sun's image on a BRICK or a paving stone. No need to start a fire!
One whos been here for to long
Hi there i have been going throught these forum for the past year and have been gathering stuff to make my projector i wanted to ask where do you get your lens? i live in Iceland and the cheapest i have found cost´s around $800 usd.
:S my layout is very simular to your´s so i was wondering if you could give me a pointer for a good lens.
I will be using a 15" LCD
Hi there
i have been going throught these forum for the past year and have been gathering stuff to make my projector i wanted to ask where do you get your lens? i live in Iceland and the cheapest i have found cost´s around $800 usd.:S my layout is very simular to your´s so i was wondering if you could give me a pointer for a good lens.
I will be using a 15" LCD
KazTraz,
www.diyprojectorcompany.com
135 mm diameter by 450 mm focal length air spaced triplet.
Exellent lens that will work for 9inch to 17 inch LCD panel.
119 USD plus shipping
Hezz
www.diyprojectorcompany.com
135 mm diameter by 450 mm focal length air spaced triplet.
Exellent lens that will work for 9inch to 17 inch LCD panel.
119 USD plus shipping
Hezz
Re: 570 mm fl lens
Have you seen these lenses at surplushed?
AEROJET DELFT 6" FL F 2.8 AERIAL CAMERA LENS SETS $60.00
CAI 6" F/2.8 KS-87B AERIAL CAMERA LENS CONE $150.00
A bit pricy though...
Guy Grotke said:
Have you seen these lenses at surplushed?
AEROJET DELFT 6" FL F 2.8 AERIAL CAMERA LENS SETS $60.00
CAI 6" F/2.8 KS-87B AERIAL CAMERA LENS CONE $150.00
A bit pricy though...
What about those :
5.25” E.F. THEATER PROJECTION LENS
or
WOLLENSAK 5” FL f 1.9 CINEMA RAPTAR PROJECTION LENS?
They are here
5.25” E.F. THEATER PROJECTION LENS
or
WOLLENSAK 5” FL f 1.9 CINEMA RAPTAR PROJECTION LENS?
They are here
Sorry guys,
None of these lenses will work with a 15 inch LCD. The two 6 inch focul length lenses from surplus shed might work with a small LCD of 5 inches or less.
Remember film projection lenses are meant to image a small piece of film. They will never work with large LCD monitors.
If you can get a LCD monitor about 2-3 inches it might work but remember they are meant for a long throw of a theater. Your room will likely not be anywere near that big. In most theaters the distance from the lens to the wall is 20 - 50 meters. Your not very likely to make a lens designed for that to work in a home theater projector.
Stay away from film projection lenses unless you are using a tiny LCD and the lens is designed for small rooms.
You can look for large format photography lenses on ebay but they do not sell for cheap.
The best deal for a 15 inch LCD is to buy one from Lumenlabs or DIYprojectorcompany or to find a surplus over head projector. These are cheap and easy to find.
Hezz
None of these lenses will work with a 15 inch LCD. The two 6 inch focul length lenses from surplus shed might work with a small LCD of 5 inches or less.
Remember film projection lenses are meant to image a small piece of film. They will never work with large LCD monitors.
If you can get a LCD monitor about 2-3 inches it might work but remember they are meant for a long throw of a theater. Your room will likely not be anywere near that big. In most theaters the distance from the lens to the wall is 20 - 50 meters. Your not very likely to make a lens designed for that to work in a home theater projector.
Stay away from film projection lenses unless you are using a tiny LCD and the lens is designed for small rooms.
You can look for large format photography lenses on ebay but they do not sell for cheap.
The best deal for a 15 inch LCD is to buy one from Lumenlabs or DIYprojectorcompany or to find a surplus over head projector. These are cheap and easy to find.
Hezz
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