The Ultimate 3D projection system: A Practical Discussion Thread - Page 78 - AVS Forum | Home Theater Discussions And Reviews
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post #2311 of 2420 Old 02-14-2015, 12:20 AM
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Originally Posted by wanderer View Post
I'm going to post some information in the 3D screens thread shortly on my thoughts on the 5D and some other screen materials I looked at.

W. Jeff Meier in his Screen material test report pretty much nails the 2D performance description for the 5D - color reproduction is excellent, it has a very smooth surface and you do get some shimmer due to the reflective elements in the screen. IMO any screen with gain has hotspotting and this is a silver screen with gain and reflective elements so it's definitely not a 'clean' 2D screen. I have an HP 2.4 Da-Lite screen as well for comparison and while that's a better screen for 2D from a 'clean' reflective elements perspective, the color reproduction isn't as good as that on the 5D.

For 2D I only use one projector which is set in ECO mode and I have the white level turned down to 13ftl from about 17-18ftl. Having one lamp age differently isn't an issue as I can recalibrate as time goes on with the Radiance units\Calman and both projectors will still match in their light output and color balance.

i think the easiest way to get riddof hotspotting is go curved.
Had for a while but dropped it down while i was waiting my omega filtters. I might Try it one more time maby some time if there comes superbly better silverscreens. Im bothered about the ghosting every silver seems to have, atleast based on samples compared to one i have.
Curved screen is pretty easy to do if you get yourself some metal/aluminiumin to make a frame and use some threaded
Rod on top and bottom attached to the screen material, just tie from the Sail holes if you have them on your screen material.
Then have some stoppers at left and right top and bottom of the frame at the screen edge level to force the threaded rod to bend backwards. Just have the frame mounted off the wall 20-30 cm with some shelf holderit so there is room for bendings.
After maskin the tie strings of the screen it even looks great and if and just if you wanna use backlight its easy to light some at the Back of the screen course its not that fixin.
Worked like charm, i loved it.
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post #2312 of 2420 Old 02-15-2015, 10:07 PM
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Quote:
Originally Posted by Vaan Janne View Post
i think the easiest way to get riddof hotspotting is go curved.
Had for a while but dropped it down while i was waiting my omega filtters. I might Try it one more time maby some time if there comes superbly better silverscreens. Im bothered about the ghosting every silver seems to have, atleast based on samples compared to one i have.
Curved screen is pretty easy to do if you get yourself some metal/aluminiumin to make a frame and use some threaded
Rod on top and bottom attached to the screen material, just tie from the Sail holes if you have them on your screen material.
Then have some stoppers at left and right top and bottom of the frame at the screen edge level to force the threaded rod to bend backwards. Just have the frame mounted off the wall 20-30 cm with some shelf holderit so there is room for bendings.
After maskin the tie strings of the screen it even looks great and if and just if you wanna use backlight its easy to light some at the Back of the screen course its not that fixin.
Worked like charm, i loved it.
I just posted in the Screens for 3D projection thread on my testing from a few different materials. The $5 DIY screen I outline there might make an interesting test to compare to your existing silver screen material and polarization retention.

Hotspotting - that's an interesting subject in itself. How wide is your screen (left to right) and how many multiples away from the screen do you have the PJs mounted? Are the PJs mounted at the top of the screen or below the top edge of the screen? My PJs are mounted more than 2x the screen width from the screen surface.
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post #2313 of 2420 Old 02-16-2015, 08:42 AM
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Quote:
Originally Posted by Vaan Janne View Post
i think the easiest way to get riddof hotspotting is go curved.
Had for a while but dropped it down while i was waiting my omega filtters. I might Try it one more time maby some time if there comes superbly better silverscreens. Im bothered about the ghosting every silver seems to have, atleast based on samples compared to one i have.
What sreens did you have? I am considering linear polarization on this one: http://screenresearch.com/website/do...eb_01_2013.pdf as it has quite small holes for audio transparency. I wanna go 4k & curved.
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post #2314 of 2420 Old 02-16-2015, 10:02 AM
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What sreens did you have? I am considering linear polarization on this one: http://screenresearch.com/website/do...eb_01_2013.pdf as it has quite small holes for audio transparency. I wanna go 4k & curved.
I had Custom made. Wax canvas painted with silver paint from awater 3D
To my experience it was pretty smooth, not so much grainy as many silver materials at 2D.

I did order many samples. Dalite ect best 3d canvases and i think the polarisation retention was as **** on these samples as in my Custom screen. I gues its ok on many movies but after watching the omega filtters the 3D effect is still so much sharper than polarized, because of the noin ghosting filtering technik.allthough i miss the color accuracy of polarized.Point of my reply is i did not find a bit worth the money to spend on expensive professional screen materials because my personal opinnion is they Were not a bit better and cost a joke.

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post #2315 of 2420 Old 02-17-2015, 02:50 PM
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Top screens like Steward 5D claim over 90% of polarization retention though. Well, and I am not sure If I can live with the color inacuracy of the Omega filters, that's why I want to go polarized.
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post #2316 of 2420 Old 02-17-2015, 05:16 PM
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Quote:
Originally Posted by zorg43x View Post
What sreens did you have? I am considering linear polarization on this one: http://screenresearch.com/website/do...eb_01_2013.pdf as it has quite small holes for audio transparency. I wanna go 4k & curved.
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Originally Posted by zorg43x View Post
Top screens like Steward 5D claim over 90% of polarization retention though. Well, and I am not sure If I can live with the color inacuracy of the Omega filters, that's why I want to go polarized.
I am thinking of the same thing. I spoke to the Stewart's distributor here in Australia and he was quite knowledgable in the passive 3d setup. I am wanting to do a 2.35 screen and he basically said that I would get a much better result with a curved screen.

The only issue with 4k is you are restricted to three companies with licensing - Sony, Christie and Barco. I had a look at Barco and Christie, they really don't have anything that is really fit for home use. That leaves Sony the only option. From most tests they the Sony's Red/Blue is going to be at 90 degree with the green making it less efficient than a JVC which is of course not really a 4k. However, there are virtually no 4k content at the moment so the JVC e-shift may give you the a close result to a Lumigan upscaled 4k image at a much lower price.

At the moment, I am incline to wait until 4k is cheaper. The extra 20k on the projector is better spent on the A-lens.
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post #2317 of 2420 Old 02-20-2015, 12:59 PM
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Like you said, it is better to wait until there are more 4k or UHD pjs available. The few Sonys there already available are still quite pricy and have quite a disadvantage - low speed HDMI. But on the other hand they're true 4k, not only UHD. I bet for the next generation of their pjs they choose different native resolution of the panels not to interfere with the professional segment.
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post #2318 of 2420 Old 02-23-2015, 04:18 AM
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Quote:
Originally Posted by zorg43x View Post
Top screens like Steward 5D claim over 90% of polarization retention though. Well, and I am not sure If I can live with the color inacuracy of the Omega filters, that's why I want to go polarized.
Measuring polarisation retention in percentage give a very poor representation of what will happen.
Screens for polarised 3D must have more than 99% polarisation retention, all these screens will fit within the last 1% but any extra decimal point will have a huge impact on screen.
In order to get a proper idea of how well it looks that value should be measured as an extinction ratio = correct polarisation / incorrect polarisation. Because that will almost be the actual amount of crosstalk you'll get (the screen is the weakest link in the chain).
Typical polarisation filters have extinction ratios above 1000:1, but screens range between 80:1 (poor screen) and 150:1 (excellent screen)

The last time I checked, Stewart provides charts on their website showing how the extinction ratio varies according to the view angle.
Edit : It seems I can't find the charts on their new website
Edit 2 : I checked harkness screens' website to see what the competition does, it looks like they went the other way, they made a higher gain, lower view angle screen but with a crazy high 270:1 extinction ratio (Spectral 300). That screen would be unusable with a flat screen, a curved screen would be mandatory with such a beast.

Passive 3D, forever !
My Full-HD dual-projector passive polarised 3D setup. (really out of date ! I need to update it some day...)


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post #2319 of 2420 Old 05-06-2015, 05:42 AM
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Measuring polarisation retention in percentage give a very poor representation of what will happen.
Screens for polarised 3D must have more than 99% polarisation retention, all these screens will fit within the last 1% but any extra decimal point will have a huge impact on screen.
In order to get a proper idea of how well it looks that value should be measured as an extinction ratio = correct polarisation / incorrect polarisation. Because that will almost be the actual amount of crosstalk you'll get (the screen is the weakest link in the chain).
Typical polarisation filters have extinction ratios above 1000:1, but screens range between 80:1 (poor screen) and 150:1 (excellent screen)

The last time I checked, Stewart provides charts on their website showing how the extinction ratio varies according to the view angle.
Edit : It seems I can't find the charts on their new website
Edit 2 : I checked harkness screens' website to see what the competition does, it looks like they went the other way, they made a higher gain, lower view angle screen but with a crazy high 270:1 extinction ratio (Spectral 300). That screen would be unusable with a flat screen, a curved screen would be mandatory with such a beast.
spectral 300 has smoothest shimmering than any of their polarized screens...atleast i think so.
Blackshark Do you think i have problem with hotspotting ?
i have manual iris in HC5 so i can close it to ridicilously dark. and i got a curved frame
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post #2320 of 2420 Old 05-08-2015, 08:52 AM
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If you want to go with a silver screen I suggest MDI strong. In the screen section I did a review of their StereoView screen. They are a screen company for the commercial theaters but can make you a smaller screen, I made my own frame. They also have a screen called HighWhite which is supposed to be even better with less sparkle and a better 2D viewing.
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post #2321 of 2420 Old 06-02-2015, 02:23 PM
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After 4 years of good and loyal services, I am looking for a replacement for my silverscreen.
The Harkness Spectral240 screen material has very good polarization retention capabilities, but it has big flaws :
-it has a high gain, and narrow view angle, creating a hotspot of very intense light in the middle, with a sharp light drop near the edges
-it's has a visible grain that make the picture look blurry, it's designed for large cinema screens, not for close-up use in the home, making it unacceptable for 2D use in the home
-it has a very strong shimmering due to the aluminium flakes embedded in the screen material's surface

I looked for better options. There are a few other silverscreen manufacturers out there that have silverscreens designed to be more balanced for 2D and 3D.
But one screen grabbed my attention : Screen Innovation's BlackDiamond 2.7 gain (the others don't keep polarization properly).
It's not a silverscreen, but it's a special material that has ambient-light-resistant properties. The 0.8 and 1.4 gain versions preserve polarization partially, but not well enough for 3D. The 2.7 gain screen is claimed to work well for polarized 3D, and I remember reading rdjam saying he owns one and it works well.

There is just one problem : I can't find good retailers in my country, and in the only shops I do find, it's expensive as hell !

Out of pure luck only google can provide, I found out about a small competitor I had never heard about : Xtrem Screens (and for good reason, their website is not done, they just provide a contact email)
I found about them by reading a french AV forum talking about their ambient-resistant screen, the Xtrem Screen Daylight. It turns out there is a thread here at AVS about this screen with all the right links and pictures https://www.avsforum.com/forum/23-scr...er-review.html
I wondered if by trying to reach the same goal, they might use the same process (by creating a similar screen to BlackDiamond, they might produce a good screen for polarised 3D).
I had a massive hint : people on the french forums mention that they have huge variations in brightness when they use active 3D glasses depending on the brand of glasses, the picture is super bright when they use the manufacturer's glasses, but very dark when using Xpand's glasses. (that's a clear polarization phenomenon right there)

I contacted them, and had a lengthy discussion with one of their technicians (I believe he is one of the founders of the company).
It turns out had a good intuition !

-Xtrem Screens Daylight ambient-light-resistant screens do maintain polarization
-it was part of the design, not a fluke
-they have had clients who tried polariszd 3D with it and they said it works
-their Daylight "reference" 1.1 gain screen is the best they offer for polarized 3D
-their Daylight 0.9 gain screen also works, but does not maintain polarization as well as their 1.1 gain screen
-an other Daylight 1.4 gain screen exists (it's the one shown in the screens at the link above), it was their first model, but they only recommended their newer 1.1 and 0.9 models, which they claim are significantly better.
-they make their screens with standard fixed frame, super-slim "zero edge" style frame, and also have a motorized rollable version
-it's still an expensive screen, but it's half the price of the Black Diamond (at least in my country)
-they are very confident in their product, they claim it's better than the Black Diamond, and are ready to offer me a full refund if I'm not happy with it
-their office in my country, near Strasbourg, a city I visit very often (Alsace power !)

I am going to give their screen a try

Passive 3D, forever !
My Full-HD dual-projector passive polarised 3D setup. (really out of date ! I need to update it some day...)


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post #2322 of 2420 Old 06-03-2015, 03:10 PM
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i tested samples of spectral 300 and 240 clarus cx220 and i was about to order the 300 because it has lesser graining of these and small amount of better extinction in terms of crosstalk but
i got stewart 5D sample from paul and i gotta say the extinction is about the same but the light output over screen is more constant and the grainines is alot lesser. actually it gives
pretty darn good 2D picture also. And the extintion is not anywhere near omega but in movies it´s much more to my liking to watch color balanced 3D allthough my omega filtter get
pretty good results. But i still use them for games after getting my silverscreen.
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post #2323 of 2420 Old 06-04-2015, 12:18 AM
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Nice report BlackShark! I would say go there to Strasbourgh and see for yourself if you are satisfied.
If they claim "it maintains polarization" - are thre any serious numbers or at least a comparison to a common material?
I have asked my dealer about Stewart 5D, which should be quite good for 3D and 2D, and for 4.1x1.8m screen size I got an offer of 4500 Euro.
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post #2324 of 2420 Old 06-04-2015, 02:16 AM
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At this time, they have not published any official measurements for passive polarized 3D. And they also probably do not have a dual-projector setup to de the measurements in their office.
From what XtremScreens told me, their previous passive polarized customer had tried regular silverscreens and were not satisfied with the compromises between ability to maintain stereo and the picture quality. The viewing room also has a little bit of ambient light.
So when the customer tried the XtremScreen Daylight, he was blown away by the overall picture quality he was getting and the passive 3D worked just as well as with silverscreens. Add the ambient-light resistant properties of the screen, and there was just no way he's send the screen back.
That's all I know, I do not have any figures or comparison pictures.

I considered visiting their office in Strasbourg before buying, but they do not have a demonstration passive polarized system in their showroom (the majority of their market uses traditional 2D and active 3D, so that's what they installed in their showroom). Since I do not have any measuring instruments either, it would have been pointless for me to bring my projectors in.
The guy from XtremScreens was so confident I would prefer his screen, he offered me a refund if I'm not satisfied, so I decided to buy one, and I'll compare it's performance with my current Spectral240 when I receive it.
The price for the 2.40m 16:9 screen, with a standard fixed frame is 2350€ (incl. 20% french VAT and shipping to my home).

I'll receive it by the end of the month.

Passive 3D, forever !
My Full-HD dual-projector passive polarised 3D setup. (really out of date ! I need to update it some day...)


Last edited by BlackShark; 06-04-2015 at 02:23 AM.
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post #2325 of 2420 Old 06-04-2015, 11:57 AM
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Quote:
Originally Posted by BlackShark View Post
At this time, they have not published any official measurements for passive polarized 3D. And they also probably do not have a dual-projector setup to de the measurements in their office.
From what XtremScreens told me, their previous passive polarized customer had tried regular silverscreens and were not satisfied with the compromises between ability to maintain stereo and the picture quality. The viewing room also has a little bit of ambient light.
So when the customer tried the XtremScreen Daylight, he was blown away by the overall picture quality he was getting and the passive 3D worked just as well as with silverscreens. Add the ambient-light resistant properties of the screen, and there was just no way he's send the screen back.
That's all I know, I do not have any figures or comparison pictures.

I considered visiting their office in Strasbourg before buying, but they do not have a demonstration passive polarized system in their showroom (the majority of their market uses traditional 2D and active 3D, so that's what they installed in their showroom). Since I do not have any measuring instruments either, it would have been pointless for me to bring my projectors in.
The guy from XtremScreens was so confident I would prefer his screen, he offered me a refund if I'm not satisfied, so I decided to buy one, and I'll compare it's performance with my current Spectral240 when I receive it.
The price for the 2.40m 16:9 screen, with a standard fixed frame is 2350€ (incl. 20% french VAT and shipping to my home).

I'll receive it by the end of the month.
and they don´t offer just the material for frame but only finished products ?
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post #2326 of 2420 Old 06-04-2015, 12:25 PM
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and they don´t offer just the material for frame but only finished products ?
I was looking for a finished product, my building-hacking skills aren't very good. My current home-made frame works well, and helped me save a lot of money when I made my system 4 years ago, but it's ugly.
I didn't ask for screen material alone.

Passive 3D, forever !
My Full-HD dual-projector passive polarised 3D setup. (really out of date ! I need to update it some day...)

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post #2327 of 2420 Old 06-04-2015, 12:45 PM
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I was looking for a finished product, my building-hacking skills aren't very good. My current home-made frame works well, and helped me save a lot of money when I made my system 4 years ago, but it's ugly.
I didn't ask for screen material alone.
did you check out the Premium HGA from MDI system ?. im eager to hear how good your screen is
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post #2328 of 2420 Old 06-04-2015, 02:05 PM
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I did not check for MDI-Strong's screens.
I am also very eager to try it.

Passive 3D, forever !
My Full-HD dual-projector passive polarised 3D setup. (really out of date ! I need to update it some day...)

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post #2329 of 2420 Old 06-05-2015, 08:25 AM
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The xtremscreen website is pretty crappy..or am i in the right page. kind of no categories ect just few pictures of screens ect.
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post #2330 of 2420 Old 06-05-2015, 08:33 AM
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The xtremscreen website is pretty crappy...
Yes it is ! (i told you their website was not done)

Waaoouuhh, they added the content of their company brochure as a welcome picture. What an amazing improvement ! (joke)
Two days ago, they just had their contact email and the "see you at IFA" youtube clip.
I believe their company is in initial "start-up" mode, where they are developping the product with a limited audience who are in-the-know and only launch it broadly later (at the next IFA trade show ?)

If you want real info about their screen, you have to call them, or browse the french forums where users review the screens.
The busyest thread I found was this one : http://www.cinetson.org/phpBB3/ecran...-9-t38125.html
I read quickly through all 81 pages : lots of people very impressed by the screen, taking pictures of how the screen looks (with ambient light) but they use it for 2D and active 3D only, none do passive 3D.

Passive 3D, forever !
My Full-HD dual-projector passive polarised 3D setup. (really out of date ! I need to update it some day...)


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post #2331 of 2420 Old 06-06-2015, 06:03 AM
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Damn, it's in french :P
Anyway, let us know, how your screen is gonna perform, I am quite excited I thought I will go for Stuart 5D but perhaps I'll change my mind
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post #2332 of 2420 Old 06-06-2015, 08:52 AM
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I am currently preparing a new alignment and crosstalk test pattern. I have some difficulties lining up my projectors properly.
Usually people use long lines, It's fine for general alignment but when you reach the fine details, you don't know which line corresponds to which projector and loose a huge amount of time going back and forth to the projector to find out you moved in the wrong way.

Here are the features :
-white crosstalk test with 5% light increment from 0% to 50% grey.
-black crosstalk test with 5% light increment from 100% to 50% grey.
-Left/Right color calibration and comparison scales with 10% light increment from 0 to 100% grey and primary colour
-bigger primary and secondary color comparison (100% colour only) for easier calibration
-marked corners and alignment lines cross-crossing the pattern for main alignment
-alignment arrows pointing at each other only displayed by one eye : to fine-tune alignment
-moire check across the sides (the small scale makes it look grey, it's actually a succession of 1-pixel wide black and white lines), the final proof things are lined up if you see sharp lines... or reveals possible scaling issues if you see moire garbage.

It's still work in progress, I've left some room for other patterns but I'm out of ideas.
Can you think of any thing I should add ?

Download : PNG FullSBS (3840x1080)
Download : MPO FullHD (thanks RBTO)

Passive 3D, forever !
My Full-HD dual-projector passive polarised 3D setup. (really out of date ! I need to update it some day...)


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post #2333 of 2420 Old 06-28-2015, 03:09 PM
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Has anyone tried the MDI screens High white 1.4. i did a intensity measure on my curved frame with 4 sample. 44 samples across the frame.
This not any scientific measurement. just took photos with my dslr at same settings and moving the sample



Hmmmm... High white is only for realD customers....
Wonder to become one with out purchasing anything

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post #2334 of 2420 Old 07-10-2015, 08:06 AM
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Originally Posted by BlackShark View Post
I am currently preparing a new alignment and crosstalk test pattern. I have some difficulties lining up my projectors properly.
Usually people use long lines, It's fine for general alignment but when you reach the fine details, you don't know which line corresponds to which projector and loose a huge amount of time going back and forth to the projector to find out you moved in the wrong way.

Here are the features :
-white crosstalk test with 5% light increment from 0% to 50% grey.
-black crosstalk test with 5% light increment from 100% to 50% grey.
-individual primary colour bright crosstalk test with 5% light increment from 0% to 50% colour.
-individual Left and Right primary and secondary color comparison for calibration
-marked corners and alignment lines cross-crossing the pattern for main alignment
-alignment arrows pointing at each other only displayed by one eye : to fine-tune alignment
-moire check across the sides (the small scale makes it look grey, it's actually a succession of 1-pixel wide black and white lines), the final proof things are lined up if you see lines... or moire garbage if it is not.

It's still work in progress, I've left some room for other patterns but I'm out of ideas.
Can you think of any thing I should add ?

Great looking test pattern BlackShark. I've downloaded it and will use it soon and give you more feedback. One comment - Using 1 pixel line widths to check for alignment might prove somewhat impractical since any amount of mis-alignment between the two images will produce moire. It would be almost impossible not have some, and even differences between lenses will produce moire. That pattern will prove useful though, to achieve axis alignment (rotation about the optical axis) between the projectors by minimizing the amount of moire observed. I wouldn't expect to get a moire-free field on all line patterns though.
Looking forward to using your test image.

Also, I've converted your file to an mpo file which can be displayed as a 3D slide on many 3D televisions. With your permission, I could post it here for those that might want to check crosstalk on their TVs (and since an LCD or Plasma TV perfectly overlays the L & R patterns, the 1 pixel test wouldn't (shouldn't) show moire since the alignment is perfect).
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post #2335 of 2420 Old 07-10-2015, 03:57 PM
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Great looking test pattern BlackShark. I've downloaded it and will use it soon and give you more feedback. One comment - Using 1 pixel line widths to check for alignment might prove somewhat impractical since any amount of mis-alignment between the two images will produce moire. It would be almost impossible not have some, and even differences between lenses will produce moire. That pattern will prove useful though, to achieve axis alignment (rotation about the optical axis) between the projectors by minimizing the amount of moire observed. I wouldn't expect to get a moire-free field on all line patterns though.
Looking forward to using your test image.

Also, I've converted your file to an mpo file which can be displayed as a 3D slide on many 3D televisions. With your permission, I could post it here for those that might want to check crosstalk on their TVs (and since an LCD or Plasma TV perfectly overlays the L & R patterns, the 1 pixel test wouldn't (shouldn't) show moire since the alignment is perfect).
I am publishing the pattern under a creative commons license. Feel free to convert it and/or redistribute it as long as you keep the creative commons license.

I have used it with my projectors. The moire tester doesn't work as well as I hoped.
I believed I'd get huge moire effects but in fact there are many times where I get a full pixel displacement, or even a full 2 pixel displacement, and from far away, I don't notice that the arrows are not lined up perfectly and I see no moire artefacts either.
I think I should modify them to have some parts with 1 pixel moire, 2 pixel moire, 3 pixel moire, etc... in order to make it more effective.

For the colour crosstalk, I now think it's a bad idea for a dual projector system. Since crosstalk is the same for all colours you get the exact same information as with the greyscale crosstalk test.
I think I should keep the focus of this pattern on dual projector alignment and calibration by replacing the colour crosstalk bars with separate L/R full-range greyscales and primary colour scales against a black background in order to calibrate brightness, contrast, color gain, offset, and saturation and have both projectors produce the same calibration.

If I wanted to make the ultimate crosstalk test, I should create one that challenges active 3D systems by crossing every possible colour combination at multiple brightnesses in order to test the ability of the screen to switch from any colour to any other colour, and not only the pure white on black like we do with dual projectors.

Passive 3D, forever !
My Full-HD dual-projector passive polarised 3D setup. (really out of date ! I need to update it some day...)

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post #2336 of 2420 Old 07-10-2015, 11:19 PM
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I think the problem with aligning is that as the projectors heat up and depending what they thow the picture changes. if i let my projectors sit on long time and everthing else goes
to sleep the projectors project blue or black on whole picture area the sharpness changes again to different position than with normal movie image. so i don´t even bother anymore
to align the images perfectly. they just don´t stay there. it´s a waste of time.
maby couple setting in geobox... cold and hot but that´s it.

Or am i missing the point of this alignment part of the test image ?
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post #2337 of 2420 Old 07-11-2015, 03:30 PM
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My projectors are stable. The lens shift doesn't move... at least as long I don't accidentally bump into the shelf.

Passive 3D, forever !
My Full-HD dual-projector passive polarised 3D setup. (really out of date ! I need to update it some day...)

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post #2338 of 2420 Old 07-11-2015, 04:26 PM
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Done !
I updated the patterns (same links as above).
Replaced the individual colour crosstalk tests with parallell Left/Right color calibration and comparison scales

Didn't do the moire update yet. Not sure i'll do it in the end.

Passive 3D, forever !
My Full-HD dual-projector passive polarised 3D setup. (really out of date ! I need to update it some day...)


Last edited by BlackShark; 07-11-2015 at 04:31 PM.
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post #2339 of 2420 Old 07-12-2015, 05:36 AM
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My projectors are stable. The lens shift doesn't move... at least as long I don't accidentally bump into the shelf.
damn you are lucky. i had panasonic ax200. they moved. and yes so do the mitsubishi.
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post #2340 of 2420 Old 07-20-2015, 02:13 PM
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Hello everybody.
I received the Xtremscreen Daylight Reference 1.1 ambient-light resistant screen. And here is my review for use with passive polarised 3D.
You'll notice I'm late. I said I'd receive it by the end of June, and I did, so what's up with the delay ? Well a few things happened. This post will be long. So I'll start with a summary :

- The Xtremscreen Daylight Reference 1.1 is amazing for 2D, and active 3D.
- It keeps barely enough polarisation to do passive polarised 3D. It's not the great screen I was hoping for in that particular aspect.
- I visited Xtremscreen's HQ in Strasbourg, France. I brought my projectors, PC and everything. We tested some prototypes of modified Daylight 1.1 screen materials.
- We find the holy grail !
- I want that special 3D screen ! Can I buy it ?!?

With that said... Let's start the review.

First of all, before even switching the projector on, I must say one thing : WOW ! It's stylish !
A true professional frame with a beautiful screen well tensionned, it's so much better than my previous amateur DIY frame I never finished and which is often badly tensionned. Let's do a before/after comparison. (my previous screen had been improperly tensionned for months and the summer heat-wave at the moment of these pics made it worse. I hate tensionning screens, so I left it like that waiting for the coming Xtremscreen screen)

Before


After

On this picture, I had just lined up the 1st projector, it was a small picture test with ambient light.
(the weather is great outside, but it's the evening, about 45 minutes before sunset, the screen is located in the most protected corner of the living room. You can guess the sun's position behind the window frame on the left)

I won't do detailed ambient-light rejection demonstrations (you'll find demonstration pictures easily enough if you google for Xtremscreen), I'll just summarize my findings in a few words :

- The ambient light rejection is significantly better than the Spectral 240, which isn't bad to start with since it's high gain and highly directional, but the Xtremscreen Daylight Reference 1.1 offers a noticeable improvement (and yet it has a much wider view angle, the lower gain probably helps).
- It's not a TV, at the Sun's apex, with the blinds fully open, it won't do miracles.
- But with controlled lights, that screen is amazing, it can do things I'd never dreamed about.
- Even if I wanted to do 2D, I'll never, ever, EVER, buy a matte white screen now that I've seen what a proper ambient-light rejecting screen can do.


Let's line up the two projectors.
I can get a more than sufficient alignment for 3D very quickly, but as soon as you look at the picture without glasses, you can immediately see if the images are not perfectly lined up to the last pixel (it's slightly blurry), and doing the perfect alignment takes a lot of time. Epson's EH-TW3500 efficient but unsophisticated lens shift doesn't help either ; as soon as I touch one axis, all the others get loose and start moving too. I usually manage to line them up to about 1 pixel, but I usually run out of patience trying to get that last pixel right. So here is my best alignment.


For 2D use, I get some blur if I leave both projectors on, so I usually just use only one projector if I want to display 2D.
For 3D use, as soon as you put the glasses on your nose, it looks really good, you'd swear the picture are perfectly lined up.

Let's compare the Xtremscreen Reference 1.1 to my previous screen Harkness Spectral 240.
The reason why I want to change screen was to solve my shimmering issues, and to reduce the amount of hotspot. So let's start by looking at these specific aspects.

Harkness Spectral240 : (pics made with a phone, sorry for the poor quality)

(the green/purple color shift is caused by the internal polarisation of my old-gen 3-LCD projectors when filtered by polarisers, it's not the screen, please focus on the shimmering and hotspot)
So the Harkness Spectral 240 is shimmering a lot ! The grey squares should look flat, but that's not at all what our eyes can see.
The material is designed for large theaters, where the audience sits at least 10m away from the screen with better seats much farther, not 3m away in a living room !
You can also see that the pure white corner of the picture looks darker than some of the grey bits in the middle of the picture : the very close proximity of the camera to the screen amplifies the hotspot significantly.

Xtremscreen Daylight Référence 1.1 : (same phone camera, same poor shot quality, sorry)

(in this case, you don't see the green/purple color shift, this is because I hadn't put the polarisers when I took the shot. Again I'm focusing on the shimmering and hotspot with this test)
Huge improvement with the Xtremscreen screen ! The grey squares do have a flat colour. You can even distinguish the pixel structure and the imperfect alignment of the 3-LCD primary colour panels.
It looks like my left projector has a lot more mis-alignment than my right projector.

The hotspot is almost gone, there is still a little bit of it since the camera is so close to the screen, but what a change !

So two very good news for a start. The Xtremscreen make an impressive start !

And now, the big moment ! Crosstalk test !
Let's put our 3D glasses on.
Since we're using a passive polarised system, the amount of crosstalk will always be proportionnal to the contrast between the two eyes, no matter the actual colour of the picture (which is very different from what happens with active shutter systems). And since our eyes' perception of light intensity is logarithmic, we can only see crosstalk in dark pictures, where a bit of bright picture in one eye bleeds into a dark area of the other eye.
The most extreme test we can build is a pure white on black crosstalk test. So this is what we'll use.

Let's start with the Harkness Spectral 240 as a starting point

We are looking through the left lens.
The crosstalk test is located in the black frame just below the lower grey scale (0~50% grey by 5% steps). In the other eye, we have filled this same area with pure white, and we'll be looking at how much of this light bleeds through to the wrong eye, and compare it to the grey scale.
The white crosstalk appears as a dark grey which is similar to the 15% grey on the scale. It's far from perfect, but it's hard to beat.

Xtremscreen Référence 1.1 :

First of all, we're noticing the difference in gain (1.1 vs 2.4) the phone's camera is already at it's maximum setting, the shot looks dark, but to the eye it's plenty bright.

For crosstalk, it's not looking good.
The white crosstalk bleeds so much it looks slightly brighter than the 25% grey, almost 30%.
It's not the end of the world but it's a lot. The Daylight Reference clearly falls short on this aspect.
I have to admit, I didn't expect it to match the polarisation retention of an actual silverscreen, but I didn't expect such a huge difference

------------------------------------

My initial conclusion is mitigated.
On one hand, the Xtremscreen Daylight Reference 1.1 absolutely ROCKS for 2D, and I haven't been able to do nice 2D for a while now (at least since the day I accidentally scratched my Harkness screen against furniture and decided I should stop moving it daily to use the white wall whenever I wanted to do 2D stuff)
The crisp, precise picture and super low amount of hotspot, with ambient-light rejection, is a clear improvement over the Spectral 240 silverscreen. It's hard to go back even for a few minutes just for testing.
But on the other hand, the jump in crosstalk is too big to ignore. Most of the time with typical content, it just works fine but the frequency of scenes where I notice the crosstalk has gone up significantly.

This screen is a compromise, I clearly feel the loss in crosstalk but all the improvements are so good I can't take the screen down. I just wish there was a way to keep that screen and make the crosstalk vanish.
I just wish....

Hey, did I just see a shooting star ?

To be continued...
Coming next : pretzels and sauerkraut, I'm going to Strasbourg, France, meet Xtremscreen's founders, and fall in love with a 30x30cm prototype screen sample.

Passive 3D, forever !
My Full-HD dual-projector passive polarised 3D setup. (really out of date ! I need to update it some day...)


Last edited by BlackShark; 07-21-2015 at 01:27 AM.
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