Very interested in a 17" panel mated to the 135mm projection lens (450mm fl) and as a result the discussion here.
I ran across this http://www.fresneloptic.com/html_en/fresnellens.htm
and particularly item Fresnel-4200510 which is 420mm by 260mm with a Focal length of 510mm
Wondered if anyone outside Nanjing, China had ever seen this item in the flesh?
I ran across this http://www.fresneloptic.com/html_en/fresnellens.htm
and particularly item Fresnel-4200510 which is 420mm by 260mm with a Focal length of 510mm
Wondered if anyone outside Nanjing, China had ever seen this item in the flesh?
I sent an email asking about price, availability, shipping costs to US, and if the corners are cut.
I'm afraid 260mm will be too small for a 17" panel, but if the corners are not cut, it should work a treat for the high res 15.4" widescreen panels.
I'll post my findings.
Thanks for the link!
I'm afraid 260mm will be too small for a 17" panel, but if the corners are not cut, it should work a treat for the high res 15.4" widescreen panels.
I'll post my findings.
Thanks for the link!
Hi friends, it is a long time since i first interested on the specs of the triplet 135 lens. Now after a disgusting answers from ones and others, i have received the true manufacturer specs for this lens.
The problem comes when the assumpions taken to the ideal fresnells lens for 15-17" was that this triplet would do a good work with them. But if we are strict and we work in pure specs based maths, we found that this triplet is no way to make it work with even 15" lcd and a rasonable throw.
This are the specs told by manufacturer; i belive they are true and i trust on them for any design we could do.
Description: Projection Triplet Lens
Construction: 3 elements AR-coated glass lenses in black anodized aluminum barrel
Diameter: 136.5mm
Barrel lengh: 150.4mm
Effective Focal Length: 450mm
Back Focal Length: 380mm
F no.: F3.6
Clear Aperture: 125mm (450/3.6=125)
Internal F-stop (midle lens aperture): 109mm
FOV: Designed to cover 11" square LCD
Max Field angle: 24 degrees full angle, (12+12 half angles)(+/- 3 degrees error)
Weight: 5 lbs/pc
Packaging: 6pcs/shipping carton
Carton size: L20" x W13" x H8"
Carton gross weight: 32 lbs
There, the most important thing we didn´t know (or was hidden by the people knew it) is the field angle, we have work out the field fresnell focal considering that the 17" lcd and a projected image size of 100" so there would be somewhere 52cm between lcd and triplet, so the used field angle would be somewhere 46 degrees, but if we check it on the lens specs, we found it is 24 the max field angle was designed for (24+3=27 degrees in the best case) so DO WE AGREE ON THIS SETUP NOW THAT WE HAVE MORE INFORMATION?
Maybe this triplet is still the best choice we can have, but we need to assume that there won´t be "corner to corner focus" if we go this way.
I still found 550 field fresnell very usefull, even if i don´t have a projection lens that i would like to be, but just wonder what do you think about this problem has just come up.
Rox
The problem comes when the assumpions taken to the ideal fresnells lens for 15-17" was that this triplet would do a good work with them. But if we are strict and we work in pure specs based maths, we found that this triplet is no way to make it work with even 15" lcd and a rasonable throw.
This are the specs told by manufacturer; i belive they are true and i trust on them for any design we could do.
Description: Projection Triplet Lens
Construction: 3 elements AR-coated glass lenses in black anodized aluminum barrel
Diameter: 136.5mm
Barrel lengh: 150.4mm
Effective Focal Length: 450mm
Back Focal Length: 380mm
F no.: F3.6
Clear Aperture: 125mm (450/3.6=125)
Internal F-stop (midle lens aperture): 109mm
FOV: Designed to cover 11" square LCD
Max Field angle: 24 degrees full angle, (12+12 half angles)(+/- 3 degrees error)
Weight: 5 lbs/pc
Packaging: 6pcs/shipping carton
Carton size: L20" x W13" x H8"
Carton gross weight: 32 lbs
There, the most important thing we didn´t know (or was hidden by the people knew it) is the field angle, we have work out the field fresnell focal considering that the 17" lcd and a projected image size of 100" so there would be somewhere 52cm between lcd and triplet, so the used field angle would be somewhere 46 degrees, but if we check it on the lens specs, we found it is 24 the max field angle was designed for (24+3=27 degrees in the best case) so DO WE AGREE ON THIS SETUP NOW THAT WE HAVE MORE INFORMATION?
Maybe this triplet is still the best choice we can have, but we need to assume that there won´t be "corner to corner focus" if we go this way.
I still found 550 field fresnell very usefull, even if i don´t have a projection lens that i would like to be, but just wonder what do you think about this problem has just come up.
Rox
strange spec!
It says 24 degree full field angle, but it also says:
"FOV: Designed to cover 11" square LCD"
An 11" square LCD would have a diagonal measurement of 15.5 inches, which is more than the diagonal measurement of a standard 15" LCD.
But an 11" square LCD would need a full field angle of around 52 degrees (for very long throws), down to around 40 degrees at short throw distances. How can a triplet with such a small field angle work with an 11" square LCD?
It says 24 degree full field angle, but it also says:
"FOV: Designed to cover 11" square LCD"
An 11" square LCD would have a diagonal measurement of 15.5 inches, which is more than the diagonal measurement of a standard 15" LCD.
But an 11" square LCD would need a full field angle of around 52 degrees (for very long throws), down to around 40 degrees at short throw distances. How can a triplet with such a small field angle work with an 11" square LCD?
field angle & throw distance
>Dont you mean that the other way round guy?
No, what I said is the correct relationship between throw distance and field angle: As the throw distance increases, the LCD to lens distance decreases, which makes the field angle go up.
But my quick estimates of the values were not great.
10 meter throw: 471 mm LCD to lens, 33.04 degree full field angle
2 meter throw: 580.6 mm LCD to lens, 27.06 degree full field angle
>Dont you mean that the other way round guy?
No, what I said is the correct relationship between throw distance and field angle: As the throw distance increases, the LCD to lens distance decreases, which makes the field angle go up.
But my quick estimates of the values were not great.
10 meter throw: 471 mm LCD to lens, 33.04 degree full field angle
2 meter throw: 580.6 mm LCD to lens, 27.06 degree full field angle
After many considerations including the cost effective, I decide to make a 350mm x 280mm fresnel lens for 17" LCD use.
As to the focal length, how about focal length 600mm?
This 600mm can meet DIY LCD projector purpose?
Please give me your opinion!
Thanks
http://www.3Dlens.com
As to the focal length, how about focal length 600mm?
This 600mm can meet DIY LCD projector purpose?
Please give me your opinion!
Thanks
http://www.3Dlens.com
Size & focal length for fresnel
If you make it 550 mm focal length, then you should make the size 360 mm by 290 mm. That gives the users 10 mm extra around each edge. This is important because they can't put the fresnel right next to the LCD. It has to be at least 20 mm before the LCD, so the rings will not be in the image.
If you make it 600 mm focal length, then most builders will want to put it about 70 mm before the LCD. So the size will have to be at least 390 mm by 310 mm.
If you make it 600 mm focal length and 350 mm by 280 mm, then builders will have a difficult time getting the edges of their LCD lit. Please make it large enough for everyone. If some builders want to trim the edges, that is very easy for us to do. Almost everyone who has built a DIY LCD projector has trimmed their fresnels.
I see from the website that you already have 395 mm by 395 mm fresnels with focal lengths of 220 mm and 330 mm. Why not just add another of that size with the long focal length?
Thanks,
Guy Grotke
If you make it 550 mm focal length, then you should make the size 360 mm by 290 mm. That gives the users 10 mm extra around each edge. This is important because they can't put the fresnel right next to the LCD. It has to be at least 20 mm before the LCD, so the rings will not be in the image.
If you make it 600 mm focal length, then most builders will want to put it about 70 mm before the LCD. So the size will have to be at least 390 mm by 310 mm.
If you make it 600 mm focal length and 350 mm by 280 mm, then builders will have a difficult time getting the edges of their LCD lit. Please make it large enough for everyone. If some builders want to trim the edges, that is very easy for us to do. Almost everyone who has built a DIY LCD projector has trimmed their fresnels.
I see from the website that you already have 395 mm by 395 mm fresnels with focal lengths of 220 mm and 330 mm. Why not just add another of that size with the long focal length?
Thanks,
Guy Grotke
Just to be honest
I think I should mention that my projector in my media room would probably work better with a 600 mm focal length field fresnel, or even a 650 mm. (I am using a longer focal length projector lens than most long-throw projector builders.)
However, I still think that most builders will prefer a 550 mm focal length fresnel, and I think 3dlens would sell more of those than if they make a 600 mm.
This presents an interesting ethical problem for me: Should I recommend the length that will work better for me, or the length that will work better for eveyone else and sell better?
Posting this is my solution.
I think I should mention that my projector in my media room would probably work better with a 600 mm focal length field fresnel, or even a 650 mm. (I am using a longer focal length projector lens than most long-throw projector builders.)
However, I still think that most builders will prefer a 550 mm focal length fresnel, and I think 3dlens would sell more of those than if they make a 600 mm.
This presents an interesting ethical problem for me: Should I recommend the length that will work better for me, or the length that will work better for eveyone else and sell better?
Posting this is my solution.
jimhuang said:
jimhuang,
550mm in size 350x280mm is to small. The fresnel has to be big enough to light the edges of the LCD. 550 in size 360x290mm is big enough.( bigger is better ) You already have 220/330mm in size 395x395. Can you make 550mm in size 395x395? That would work for 15,17 and 19 inch LCDs. One size for everybody.
I agree with Guy. 650 fl would be better. Its much easier to get the whole image clean and crisp with a narrower angle. Rox has been all over that problem.
I dont think you would sell more at 550 unless you mean people that are unhappy and have to buy a second! LOL That won't do anyone any favor. Im using a big OHP lens with 330 fl. This was designed for a big stage. Most of you guys are getting the 135mm lens which cant handle that big an image at that range.
The long projector is not really a problem because a tall design like a tower speaker eliminates the keystone issue. If you want a shelf unit go folded.
A quality image is going to make a lot more people happy than a slightly smaller box.
I dont think you would sell more at 550 unless you mean people that are unhappy and have to buy a second! LOL That won't do anyone any favor. Im using a big OHP lens with 330 fl. This was designed for a big stage. Most of you guys are getting the 135mm lens which cant handle that big an image at that range.
The long projector is not really a problem because a tall design like a tower speaker eliminates the keystone issue. If you want a shelf unit go folded.
A quality image is going to make a lot more people happy than a slightly smaller box.
A 650mm fresnel would have to be placed further away from the LCD than a 600mm frensel would if used with the 135mm triplet. Which is fine in a unsplit design but there are also unsplit designs to consider. A 550mm fresnel would work in both designs. Is it a compromise? Yes. But the bottom line is it 's all about sales for 3Dlens.com. They would benefit from producing a product that the most amount of people can use.
Me2! said:
The 550mm fresnel is more complementary for the 135mm lens in an unsplit design (post #20) unless of course you're using a longer focal length triplet. The 550mm fresnel can also be made to work in a split design as well. As far as being "cheaper to have a lens made that is correct at the smaller angle", I wouldn't know. Whatever focal length fresnel 3Dlens does produce, I'm hopeful that it will work in both designs, even if one design needs more "tweaking" than the other.
I didn´t want to post it here but here it is;
Yes, 550mm focal and 135 triplet match perfectly. But what does not match is 17" and 135 triplet. Honestly, there are issues with 15" and 135 triplet, so how the hell will it work with 17"?
the only way for working with 17" is stripping the 135 triplet, but then it is not 450 EFL (but 500EFL?). So I hold 600mm focal fresenll is recomendable. I find 550 much better than 330 actual fresnells, so do whatever you want cos any of them will work nice with a litle lamp adjustment.
Yes, 550mm focal and 135 triplet match perfectly. But what does not match is 17" and 135 triplet. Honestly, there are issues with 15" and 135 triplet, so how the hell will it work with 17"?
the only way for working with 17" is stripping the 135 triplet, but then it is not 450 EFL (but 500EFL?). So I hold 600mm focal fresenll is recomendable. I find 550 much better than 330 actual fresnells, so do whatever you want cos any of them will work nice with a litle lamp adjustment.
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