Minoten,
Unfortunatly, I have yet to receive my optics from DIYPC. 33 days and they still have not shipped. I will certainly let you know as soon as they arive.
I have not been able to get much done at all even though I have everything I need except my fresnels and triplet. Once I have these I can start my mock up and update my plans accordingly.
Below is my latest plans based on measurements provided by several users of simmilar optics. They tend to change often (normally for the better 😉 )
Unfortunatly, I have yet to receive my optics from DIYPC. 33 days and they still have not shipped. I will certainly let you know as soon as they arive.
I have not been able to get much done at all even though I have everything I need except my fresnels and triplet. Once I have these I can start my mock up and update my plans accordingly.
Below is my latest plans based on measurements provided by several users of simmilar optics. They tend to change often (normally for the better 😉 )
Attachments
Blue is the widest angle of light that will be needed to light the entire vertical surface of the LCD. Red is the same but for the horizontal surface. I normaly trace the diagnal distance also, but it is not shown in that drawing.
I trace those lines for several reasons:
I can get a good idea if my reflector is of suffent size to evenly light the entire LCD. (Turns out that the IKEA Napkin holders should work great.)
I can measure the max angle of light as it is hitting the triplet
I can get a rough idea as to how large my fresnels will need to be, and therefore the size of my box.
I can also tell how big my FS Mirror will need to be.
I trace those lines for several reasons:
I can get a good idea if my reflector is of suffent size to evenly light the entire LCD. (Turns out that the IKEA Napkin holders should work great.)
I can measure the max angle of light as it is hitting the triplet
I can get a rough idea as to how large my fresnels will need to be, and therefore the size of my box.
I can also tell how big my FS Mirror will need to be.
ok thats what i thought
anyway i have been working on your pic, look at this atached file at the botom;
i drow a red square inside the triplet lens (rear lens). I think you could paint the rear lens outside (non red part) with black flat and you wouldn´t notice any difference since there is no light hiting there. Is just a thought, i am discussing with guy grotke at other trhead, but i think you are not using full triplet area.
tell me what yo think about
anyway i have been working on your pic, look at this atached file at the botom;
i drow a red square inside the triplet lens (rear lens). I think you could paint the rear lens outside (non red part) with black flat and you wouldn´t notice any difference since there is no light hiting there. Is just a thought, i am discussing with guy grotke at other trhead, but i think you are not using full triplet area.
tell me what yo think about
Attachments
Minoten,
What are your current distances?
Arc <-> Fresnels <-> LCD <-> Center of Triplet
Did increasing your fresnel to LCD distance increase contrast and or color saturation?
What reflector did you go with?
Have you tried a split fresnel config yet?
I understand you can get the triplet apart pretty easily without damaging it. Have you experimented with this yet?
Sorry for all the questions, your the only one I know thats getting anywhere whith this LCD
Thanks in advance,
What are your current distances?
Arc <-> Fresnels <-> LCD <-> Center of Triplet
Did increasing your fresnel to LCD distance increase contrast and or color saturation?
What reflector did you go with?
Have you tried a split fresnel config yet?
I understand you can get the triplet apart pretty easily without damaging it. Have you experimented with this yet?
Sorry for all the questions, your the only one I know thats getting anywhere whith this LCD
Thanks in advance,
Rox,
I understand what you are getting at. Right now, all I have to go by is information from others, at least until I get my optics. It looks like you may not be able to focus the LCD if you shorten the LCD <-> Triplet distance enough to take advantage of the entire FOV. As far as I know, no one even knows the true FOV of this lens. Its all an (somewhat 😉 )educated guess at this point.
I understand what you are getting at. Right now, all I have to go by is information from others, at least until I get my optics. It looks like you may not be able to focus the LCD if you shorten the LCD <-> Triplet distance enough to take advantage of the entire FOV. As far as I know, no one even knows the true FOV of this lens. Its all an (somewhat 😉 )educated guess at this point.
thanks for the reply;
i don´t mean to shorten the lcd triplet distance, it is what it needs to be, but you can choose a field fresnell long enought or just place the bulb at a proper place so the light cone from the lcd hits full area on the rear lens element on the triplet.
of course, taking the triplet closer to the lcd would fill the area but the image should not be focused for that throw (you would have a larger trow).
you know some OHP have a wheel so the bulb placenemt can be adjusted, i believe it is if the throw changes to much, then you need to adjust the light cones again.
thanks.
i don´t mean to shorten the lcd triplet distance, it is what it needs to be, but you can choose a field fresnell long enought or just place the bulb at a proper place so the light cone from the lcd hits full area on the rear lens element on the triplet.
of course, taking the triplet closer to the lcd would fill the area but the image should not be focused for that throw (you would have a larger trow).
you know some OHP have a wheel so the bulb placenemt can be adjusted, i believe it is if the throw changes to much, then you need to adjust the light cones again.
thanks.
Um... isn't the light hitting the edges of the triplet(Therefore diminishing or destroying the corners of the image) what everyone's trying to AVOID? That's hard enough for most people. Don't be concerned with it not occupying the whole FOV of the lense.
Beyond that, the function of increasing/decreasing the distance from the fresnel affects both focus(which can be corrected if you have a varifocal lense) and throw. Several have used low focal length fresnels and a movable triplet to implement a zoom lense, using the Lumenlabs pro kit. Not nearly as easy/versatile as a commercial projector, but enough to vary the throw by 10-15% or so.
Beyond that, the function of increasing/decreasing the distance from the fresnel affects both focus(which can be corrected if you have a varifocal lense) and throw. Several have used low focal length fresnels and a movable triplet to implement a zoom lense, using the Lumenlabs pro kit. Not nearly as easy/versatile as a commercial projector, but enough to vary the throw by 10-15% or so.
Unfortunatly, the ideal FL and size field fresnels are not currently available in DIY price ranges (450-550mm). If LumenLab ever gets thier Pro fresnels in, we would have an ideal solution.
I plan on taking the Long-Throw Triplet apart and testing with diffrent lens spacing and see what I can come up with.
I plan on taking the Long-Throw Triplet apart and testing with diffrent lens spacing and see what I can come up with.
Squalish said:
If your reffering to the red rays in the right image, those rays are not folded and are not representive of where the light would be entering the lens. The left most image is correct and all light enters the triplet well within its FOV.
Inkog: A fresnel doesn't need to be used at its focal point, necessarily, as long as it's on the focal axis. Theoretically, you give up some light evenness with this(Due to the light hitting the panel at a non-perpendicular angle), but it seems that people are putting out good results this way anyway.
Given a set of two 330mm fresnels, for example, you can put a lamp closer than 330mm to the fresnel, at a point which will make the beam extend to a point 450mm ahead of the front fresnel.
Given a set of two 330mm fresnels, for example, you can put a lamp closer than 330mm to the fresnel, at a point which will make the beam extend to a point 450mm ahead of the front fresnel.
Yes I'm aware of this. My current plans use 2 330mm fresnels. Arc to fresnel distance of ~191mm, fresnel to triplet distance of ~451mm. Unfortuantly, I know of no one whom has been able to get a perfectly lit and focused projection with a >15" panel using 330's and this triplet.
I would like to find a 450mm fresnel so I can use a split design, have a keystone option, and have good light distribution. This setup would be ideal for me, but I'm going to make do with what is available to me at the present time.
Who knows, once I get my optics and start experimenting, I may find this setup works perfectly for me. Like I said before... until I get my optics, it's all guess work and assumptions.
I would like to find a 450mm fresnel so I can use a split design, have a keystone option, and have good light distribution. This setup would be ideal for me, but I'm going to make do with what is available to me at the present time.
Who knows, once I get my optics and start experimenting, I may find this setup works perfectly for me. Like I said before... until I get my optics, it's all guess work and assumptions.
Inkog,
LumanLabs has 650 mm FL field fresnels which are just about perfect for the DIYprojectorcompany 135 mm x 450 mm FL triplet.
Also remember that if you take apart your lens and move any of the lens to lens spacings you will be reducing the quality of your picture. While you may change the relative focul length to something closer to what you want you will also diminish the chromatic correction that has been built into the lens. The lens spacings are very exact and are specific to those lenses and likely cannot be altered without lowering the resolution of the lens system. You should be aware of this before you proceed.
The split fresnel approach has better light uniformity because the light is moving more perpendicular through the LCD and it also gathers more of the total light, but it has lower image quality because fresnel lenses are not good to image through.
Also when you place the field fresnel after the LCD it becomes part of the objective imaging system and will through all of the chromatic lens corrections totally off. It will blur the image to some degree. If you were going to be using a really low quality LCD some image blurring might actually help the picture by hiding screen door effect. But it is not a desireable approach if you are trying to image the LCD as perfect as possible so that your picture quality reflects you LCD quality.
Hezz
LumanLabs has 650 mm FL field fresnels which are just about perfect for the DIYprojectorcompany 135 mm x 450 mm FL triplet.
Also remember that if you take apart your lens and move any of the lens to lens spacings you will be reducing the quality of your picture. While you may change the relative focul length to something closer to what you want you will also diminish the chromatic correction that has been built into the lens. The lens spacings are very exact and are specific to those lenses and likely cannot be altered without lowering the resolution of the lens system. You should be aware of this before you proceed.
The split fresnel approach has better light uniformity because the light is moving more perpendicular through the LCD and it also gathers more of the total light, but it has lower image quality because fresnel lenses are not good to image through.
Also when you place the field fresnel after the LCD it becomes part of the objective imaging system and will through all of the chromatic lens corrections totally off. It will blur the image to some degree. If you were going to be using a really low quality LCD some image blurring might actually help the picture by hiding screen door effect. But it is not a desireable approach if you are trying to image the LCD as perfect as possible so that your picture quality reflects you LCD quality.
Hezz
Hezz,
Thanks for the info on the lens. I have been told that the triplet can be taken apart without damaging it in any way. I figured I would do some experimenting with it, if I found that I was unable to focus or had dark corners. I hope this will not be nessisary.
Still no optics 😡 I haven't even gotten a reply to my emails. I am not a happy camper
Here is an update to my plans. On the right is my light box/engine design. 100% adjustable for fine tuning. Comments welcome.
Thanks for the info on the lens. I have been told that the triplet can be taken apart without damaging it in any way. I figured I would do some experimenting with it, if I found that I was unable to focus or had dark corners. I hope this will not be nessisary.
Still no optics 😡 I haven't even gotten a reply to my emails. I am not a happy camper
Here is an update to my plans. On the right is my light box/engine design. 100% adjustable for fine tuning. Comments welcome.
Attachments
please, could you 135 triplet owners ask the seller you get it from the field angle the lens is capable of working?
i can´t believe nobody knows it. amazing
i can´t believe nobody knows it. amazing
Inkog,
Be patient. DIYprojector company has always come through for me but the way he gets his inexpensive prices is that he has to order in lots of ten or twenty at a time from his manufacturer. These are small orders by the manufacturers point of view so they are often delayed. Because he is a small operation he cannot afford to keep much stock on hand and he does not get high priority with his manufacturer.
I also don't think Allen anticipated how popular these lenses would become.
Anyway, I am sure that if you have any dark edge problems it will not be caused from the lens. At least not compared to the old triplets that are being used. The lens is not the problem. Once you get the lens in your hand and experiment a little you will see how good it is compared to the old 80mm FL triplets that most were using in the past. If you have any dark edge problems with this lens it is a light engine problem not the lens. At least not with a 15.4 inch LCD.
You may have to adjust your projector cabinet lengths to accomodate what fresnels are realistically available. But I can tell you that 650mm FL is the ideal field fresnel for that lens. You can use any FL condenser fresnel that you can find and is large enough to cover the LCD.
LumanLabs may have the fresnels on back order but you should be able to get one eventually.
Hezz
Be patient. DIYprojector company has always come through for me but the way he gets his inexpensive prices is that he has to order in lots of ten or twenty at a time from his manufacturer. These are small orders by the manufacturers point of view so they are often delayed. Because he is a small operation he cannot afford to keep much stock on hand and he does not get high priority with his manufacturer.
I also don't think Allen anticipated how popular these lenses would become.
Anyway, I am sure that if you have any dark edge problems it will not be caused from the lens. At least not compared to the old triplets that are being used. The lens is not the problem. Once you get the lens in your hand and experiment a little you will see how good it is compared to the old 80mm FL triplets that most were using in the past. If you have any dark edge problems with this lens it is a light engine problem not the lens. At least not with a 15.4 inch LCD.
You may have to adjust your projector cabinet lengths to accomodate what fresnels are realistically available. But I can tell you that 650mm FL is the ideal field fresnel for that lens. You can use any FL condenser fresnel that you can find and is large enough to cover the LCD.
LumanLabs may have the fresnels on back order but you should be able to get one eventually.
Hezz
i see you believe o the lens specs, but actually don´t know the specs. Do you know where can be the specs found?
Inkog,
Your overall design looks pretty good. There are now a few things to think about in regards to the bulb and reflector.
One, a lot of light is lost out the sides and if you can get the reflector to come up around the bulb to it's midpoint you will reflect more light (in theory).
I have come up with an idea that I think will improve the light reflectors that are being used. I think it will work with both spherical and parabolic reflectors.
Since the actual light element is far from being a point source all of the reflectors that we are using are far from ideal. I have come up with some reflector geometries that I think will work better than standard shapes for non point source elements.
I will discuss more of this on my projector thread in the next few days.
Hezz
Your overall design looks pretty good. There are now a few things to think about in regards to the bulb and reflector.
One, a lot of light is lost out the sides and if you can get the reflector to come up around the bulb to it's midpoint you will reflect more light (in theory).
I have come up with an idea that I think will improve the light reflectors that are being used. I think it will work with both spherical and parabolic reflectors.
Since the actual light element is far from being a point source all of the reflectors that we are using are far from ideal. I have come up with some reflector geometries that I think will work better than standard shapes for non point source elements.
I will discuss more of this on my projector thread in the next few days.
Hezz
I already have both my bulb and reflector and by my calculations the reflector is big enough to reflect light back through the arc at at all the angles needed to light the fresnels from corner to corner. Any bigger and you would just be reflecting light and IR heat back through the bulb at angles that would not hit the fresnels anyway.
I hope that makes sense. 😉
I would love to hear/see your new ideas.
I hope that makes sense. 😉
I would love to hear/see your new ideas.
I have all my optics, and am messing around with them as we speak. I have a horizontally folded design, and after tons of tweaking i still cant get the whole picture totally focused...but who knows.
I can tell you one thing, dont plan on going with the 5.5" Fresnel->Bulb and 15.5" LCD->Triplet like alan says, its more like 8" Fresnel->Bulb and 18" LCD->Triplet.
Ill try to take some pictures today of my setup and of the corner problems.
At 7.5" away from the bulb, my fresnels still produce dark corners, looks like I need to push the bulb back some more.
I can tell you one thing, dont plan on going with the 5.5" Fresnel->Bulb and 15.5" LCD->Triplet like alan says, its more like 8" Fresnel->Bulb and 18" LCD->Triplet.
Ill try to take some pictures today of my setup and of the corner problems.
At 7.5" away from the bulb, my fresnels still produce dark corners, looks like I need to push the bulb back some more.
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