a long focal lengh would do a good work, but i don´t know if there is any available for us.
actually "ben_tech" did a 15,4" wodescreen based projector with a varifocal, i believe the varifocal has much better field angle than the 135 triplet so it does work nicelly. But he sais there is some blur on corners as well, and the throw he used (suficent for him) is something short, for most of us.
Guy grotke aslo uses projecton lenses with somewhere 600mm focal, this gives him good focus from corner to corner.
what about those people that posted they would try to convince me here with photos (first page on this trhead), changed your opinion?
Rox
actually "ben_tech" did a 15,4" wodescreen based projector with a varifocal, i believe the varifocal has much better field angle than the 135 triplet so it does work nicelly. But he sais there is some blur on corners as well, and the throw he used (suficent for him) is something short, for most of us.
Guy grotke aslo uses projecton lenses with somewhere 600mm focal, this gives him good focus from corner to corner.
what about those people that posted they would try to convince me here with photos (first page on this trhead), changed your opinion?
Rox
340mm FL triplet and 510mm FL fresnel
Guys,
Is 340mm FL triplet a nice combination with 510mm FL Fresnel for 17" or 15"?
Would it produce corner to corner sharpness?
Thanks.
Guys,
Is 340mm FL triplet a nice combination with 510mm FL Fresnel for 17" or 15"?
Would it produce corner to corner sharpness?
Thanks.
Re: 340mm FL triplet and 510mm FL fresnel
510 mm focal field would only focus full light on short throws for this projection lens; (assume unsplit and 20mm gap)
1/34=1/49 + 1/throw
throw=111 cm, really short throw.
larger throw would need less lcd triplet separation and this would not allow the field fresnell to condense light properly into the projection lens. I find this setup wrong.
buddy123 said:
510 mm focal field would only focus full light on short throws for this projection lens; (assume unsplit and 20mm gap)
1/34=1/49 + 1/throw
throw=111 cm, really short throw.
larger throw would need less lcd triplet separation and this would not allow the field fresnell to condense light properly into the projection lens. I find this setup wrong.
build projection lens for 15" and 17"
Can I interrogate?
Who knows someone?
Man for himself build projection lens for 15" and 17"?
Can I interrogate?
Who knows someone?
Man for himself build projection lens for 15" and 17"?
posted by Inkog
I take that challenge with my 15.4" WS.
I hope I can prove you wrong!
An externally hosted image should be here but it was not working when we last tested it.
BORING!!!!!
(take it with humor)
Hi Rox , I think you are very wrong thinking that the 135 triplet not work with the 17" lcd...
I have the lens (in the matter of fact I have 2 of them , and a lot of other similar lenses , and this is the best lens I put my hands on...)
It will work very good (perfect focus) up to 19" !
I think people are with some design problems (fresnel?)
I not build my lcd projector yet , but I will put here some experiments I done.
First , I bought the lens following the guides to make a tv projector as seen on the diyprojectionTV list. When the lens arrived , I started to noticed that they will do a excelent job when in a lcd projector. But I didn´t stopped my first project , the tv projector.
Here is the lens mounted on my TV projector. This tv set is made by LG Electronics , its a 21" flatscreen TV.
You will notice in the picture that´s possible to see far trough the 21" CRT. It´s possible to see even the silver plastic from the tv.
This tv set is made by LG Electronics , its a 21" flatscreen TV.
This is like the projection image looks. My camera isn´t good to take pictures on the dark.
One more projected image:
This is a picture from the bottom of the projected image. Look that sharp focus. This picture didn´t come ever close to the real (as I said , my camera doesn´t take good pictures on the dark)
This is from the center of the screen , the very same good focus.
The focus is perfect up to 19 1/2 - 20 inches diameter , then started to blur a little.
Then I decided to make a test with a led torch to try to "discover" the fov.
The maximum angle of view was about 60 degrees !
At about 450mm , 580 usable milimeters
Some videos:
on the table...
http://www.headsoft.com.br/frh/supertelao/100-0003_MVI.AVI
from the 23" box...
http://www.headsoft.com.br/frh/supertelao/100-0001_MVI.AVI
I think it will work very well up to a 19" lcd , and if people are with trouble getting goog results with this lens , it´s only by fresnels fault.
I have the lens (in the matter of fact I have 2 of them , and a lot of other similar lenses , and this is the best lens I put my hands on...)
It will work very good (perfect focus) up to 19" !
I think people are with some design problems (fresnel?)
I not build my lcd projector yet , but I will put here some experiments I done.
First , I bought the lens following the guides to make a tv projector as seen on the diyprojectionTV list. When the lens arrived , I started to noticed that they will do a excelent job when in a lcd projector. But I didn´t stopped my first project , the tv projector.
Here is the lens mounted on my TV projector. This tv set is made by LG Electronics , its a 21" flatscreen TV.
You will notice in the picture that´s possible to see far trough the 21" CRT. It´s possible to see even the silver plastic from the tv.
An externally hosted image should be here but it was not working when we last tested it.
This tv set is made by LG Electronics , its a 21" flatscreen TV.
An externally hosted image should be here but it was not working when we last tested it.
This is like the projection image looks. My camera isn´t good to take pictures on the dark.
An externally hosted image should be here but it was not working when we last tested it.
One more projected image:
An externally hosted image should be here but it was not working when we last tested it.
This is a picture from the bottom of the projected image. Look that sharp focus. This picture didn´t come ever close to the real (as I said , my camera doesn´t take good pictures on the dark)
An externally hosted image should be here but it was not working when we last tested it.
This is from the center of the screen , the very same good focus.
An externally hosted image should be here but it was not working when we last tested it.
The focus is perfect up to 19 1/2 - 20 inches diameter , then started to blur a little.
Then I decided to make a test with a led torch to try to "discover" the fov.
The maximum angle of view was about 60 degrees !
An externally hosted image should be here but it was not working when we last tested it.
At about 450mm , 580 usable milimeters
An externally hosted image should be here but it was not working when we last tested it.
Some videos:
on the table...
http://www.headsoft.com.br/frh/supertelao/100-0003_MVI.AVI
from the 23" box...
http://www.headsoft.com.br/frh/supertelao/100-0001_MVI.AVI
I think it will work very well up to a 19" lcd , and if people are with trouble getting goog results with this lens , it´s only by fresnels fault.
woohoo, somebody that did actual, real, testing on the 18" triplet! I did similar tests on a copy lens with good results. Hopefully this will end all the bickering. We just need better fresnels!
Close.
The question is not whether light can go through at high angles its whether the lens can image at high angles. These are not the same. All lenses are very accurate in the middle and can pass light through the edges. Rox's own picture had an image in the corners but it got blurred.
Maybe it is the fresnels fault. Still need a test to be sure.
The question is not whether light can go through at high angles its whether the lens can image at high angles. These are not the same. All lenses are very accurate in the middle and can pass light through the edges. Rox's own picture had an image in the corners but it got blurred.
Maybe it is the fresnels fault. Still need a test to be sure.
Heh, did you see the screenshots above? Looks mighty crisp to me, well lit and focused at the corners. We need longer FL fresnels!
oops,
I watched the avi files (very cool btw) and didnt see the picture at the top.
If this is 19" diag then that is that.
I watched the avi files (very cool btw) and didnt see the picture at the top.
If this is 19" diag then that is that.
supahcool said:
thanks for you post, it is exactly what i was looking for.
now, let's coment some points:
the field angle is not meassured where you measured but at the optical center of the lens.
also the light test or laser test (done by a very good friend with this same triplet) won´t tell you the field angle. This will only tell you the max light angle going throw the lens, but the field angle is another thing. Abiously the field angle will be smaller than "laser angle".
I haven´t found yet someone that could xplain the definition of Field angle, If we knew this, we could meassure it but until then, all field angle meassuremts are complete subjetive measurements, something like "that's my aceptable field angle".
also let me tell you it is 24 degrees the stated field angle for this lens. (far from your 60degrees)
let me tell you also, the laser test on the 80triplet (32cm focal standar) will give you 120 degrees of angle measurement, but does it mean it will have such field angle? no, i guess somewhere 45 degrees is the stated field angle for this lens. Let's see then, if 120 laser test does have somewhere 45 degrees fov, we could say; 60 laser test of 135 triplet will have somewhere 22 degrees, well, it does match with the stated 24 degress.
also, your tests are made practially 1:1 image rate, this means a extremelly short throw. Would like to see what happens with larger throw. You know, larger throw brings the triplet closer to the source and here comes the problem.
http://www.diyprojectorcompany.com/phpBB2/viewtopic.php?t=101&postdays=0&postorder=asc&start=135
this is a user from diylabs that did test the lens as you but he had a larger throw and a smaller crt (14"?)
by the way, did you invert the vertical wires on your crt? the image is well on the projecton so i guess you did.
Why do you say it's 1:1? I can't imagine he'd show us a 19" projection of a 19" tv??? What would be the point?
Looking at the pixels shot it seems blown up. What is the size of the projection?
Looking at the pixels shot it seems blown up. What is the size of the projection?
the angle test on the videos, is done with 1:1 rate (check it) that means the lcd triplet distance is equal to the throw.
I would like him to post the throw of his projected images, tell us also the image size, please.
I would like him to post the throw of his projected images, tell us also the image size, please.
I don´t think it´s appears to , but I didn´t make the test with that 1:1 "ratio".
again , I did the test with a 21" flatscreen tv. As I said , from the 21" diagonal , a little less than 20" had perfect focus from the center to the borders. I´m sure that if we do the same test with a 19" flatscreen tv , we will see a perfect focus and lit from corner to corner. This projected image worths a lot more than a bunch of numbers (even more to me , I don´t have any optics skills)
I didn´t measure very well, but the experiments were made with a throw distance of about 2 - 2,5 meters. At about 3 meters of throw , the projected image from the 21" flatscreen tv is about 2,5x1,90 meters (I´m 1,85m tall), but don´t forget that I didn´t measure it with good precision (I don´t have enough time right now).
I will do the torch test with 2 others triplets , a fuji-xerox copy lens and with a Proj. Optics CO 14" inch triplet (the two have similar sizes) , will post the results here in the next days. But I´m sure the results will be a lot worst than the 135mm triplet.
again , I did the test with a 21" flatscreen tv. As I said , from the 21" diagonal , a little less than 20" had perfect focus from the center to the borders. I´m sure that if we do the same test with a 19" flatscreen tv , we will see a perfect focus and lit from corner to corner. This projected image worths a lot more than a bunch of numbers (even more to me , I don´t have any optics skills)
I didn´t measure very well, but the experiments were made with a throw distance of about 2 - 2,5 meters. At about 3 meters of throw , the projected image from the 21" flatscreen tv is about 2,5x1,90 meters (I´m 1,85m tall), but don´t forget that I didn´t measure it with good precision (I don´t have enough time right now).
I will do the torch test with 2 others triplets , a fuji-xerox copy lens and with a Proj. Optics CO 14" inch triplet (the two have similar sizes) , will post the results here in the next days. But I´m sure the results will be a lot worst than the 135mm triplet.
i only refered to your torch test, this is realy close to 1:1 rate.
2M trhow would give you 58cm separation from the TV to the triplets optical center, and this separation with 20" diagonal TV would need 47,3 degrees ability projection lens to have a focused image from corner to corner. And you are saiyng that field angle stated at 24 degrees projection lens does good job focusing from corner to corner (20") when double field angle ability is needed. It´s hard to understand this.
2M trhow would give you 58cm separation from the TV to the triplets optical center, and this separation with 20" diagonal TV would need 47,3 degrees ability projection lens to have a focused image from corner to corner. And you are saiyng that field angle stated at 24 degrees projection lens does good job focusing from corner to corner (20") when double field angle ability is needed. It´s hard to understand this.
Sorry , it could be hard to you to understand but for me it is very easy to see , as I said before I have 2 of these lens and , one more time , a picture worth a thousand words.
I don understand why you keep doubting the results. Keep in mind that maybe the company informed you wrong data , or this data are being missunderstood. If not , you must buy the lens or take one to do some tests by yourself.
Marcio
I don understand why you keep doubting the results. Keep in mind that maybe the company informed you wrong data , or this data are being missunderstood. If not , you must buy the lens or take one to do some tests by yourself.
Marcio
supahcool said:
yes, it could be posible as well. Sorry, i don´t mean It doesn´t work anyway, if you find it fine for you then congratulations.
I only, heard about people having focusing issues (you said it is fresnell problem most of times) I agrre in part with you. A propper fresnell helps on a better image in my opinion but it won´t do miracles. Remenber that diyeitor has 330 fresnell with 500mm focal projection lens, and his images are one of the best ones on the website.
Please answer to me, did you reversed the image on your TV?
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