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post #121 of 310 Old 01-30-2011, 09:54 PM
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Based on the title of this thread, I think it would be really good place to cover screens made for polarised projection systems using passive glasses.

I'll be getting a bunch of screen samples soon and I've designed a test pattern to test their polarisation retention.

If it's OK, I'll come back to this thread and post results over the next couple of weeks...
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post #122 of 310 Old 01-31-2011, 12:47 PM - Thread Starter
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Quote:
Originally Posted by rdjam View Post

Based on the title of this thread, I think it would be really good place to cover screens made for polarised projection systems using passive glasses.

I'll be getting a bunch of screen samples soon and I've designed a test pattern to test their polarisation retention.

If it's OK, I'll come back to this thread and post results over the next couple of weeks...

Thanks -

Once you get the results, I can update Post #1 to add the info there.

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post #123 of 310 Old 02-01-2011, 08:26 AM
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Originally Posted by Ron Jones View Post

Perhaps the lack of a response to your post is due to a lack of first hand experience by AVS Forum members that are following this thread with the Greyhawk RS screen material (sorry but I have very little experience with Stewart screens). In general I'm not a big fan of grey screens and for use with a new ceiling mounted JVC RS40 projector I would go with a white screen with a gain in the range of 1.3. If that screen retains some significant amount of the polarization of the projected light (such as the Stewart Studiotek 1.3) then for 3D viewing, while using the JVC 3D shutter glasses, you will get an extra boost in image brightness.

Hi Ron,

I hope you don't mind a few basic questions.

Is your preference to not use a grey screen with the JVC RS40 due to the fact that the projector has very good contrast and therefore doesn't need help from a screen?

I have an existing 120" Stewart Firehawk screen and I've been considering upgrading to the RS40 from a bright DLP projector. I know that you don't have experience with the Firehawk, but I was hoping you might elaborate on the generic issues involved in using a grey screen with the RS40. Is it harder to calibrate to the standard?

In reading the RS40 calibration thread I am very concerned that the calibrated brightness can be 50% or less than the published specification. In addition, I read that as the JVCs lamps age they lose a significant amount of brightness, maybe 20%-50% more. Would a grey screen permit a wider iris setting and greater brightness than a white screen with the same gain?

Thanks.

Larry

P.S. My questions are primarily geared toward the 2D performance of the JVC/Firehawk combination, but I suppose if brightness is an issue in 2D it would be an even greater issue in 3D.
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post #124 of 310 Old 02-01-2011, 09:13 AM
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Last night I was viewing some Da-lite, Stewart, Draper and Seymour samples taped up on a wall, and then used reversed RealD glasses to compare polarization. My RS40 is mounted at 7ft lens height and 22ft throw distance. Screen size set to 120" diag 16:9, with the bottom at 26" from floor.

Based on this "subjective" test, the Da-lite materials matched the results already posted.

Here are some observations that differ significantly from the chart posted on the 1st page:

- Seymour XD (AT material) had 0.

- The Stewart Studiotech 130 G3 w/Microperf, and a non-perf Studiotech 100 showed 0 polarization.

- The Stewart Firehawk G3 had 100% polarization. THIS IS AN UNDERSTATEMENT. Rating the polarization of this material is on a completely different level than all of the others. On a scale of 1-4 polarization, the Firehawk G3 rates a 10 as it goes completely black.

While some other samples rated a 3.5 or 4 on the polarization scale, in horizontal testing (correct orientation for JVC) the Firehawk G3 is bright (meeting the 1.25 gain expectations), however in the vertical test (incorrect for JVC projectors) this material went 100% BLACK. No other material came close to this extreme polarization level.

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post #125 of 310 Old 02-01-2011, 10:04 AM
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Quote:
Originally Posted by coolplazma View Post
Last night I was viewing some Da-lite, Stewart, Draper and Seymour samples taped up on a wall, and then used reversed RealD glasses to compare polarization. My RS40 is mounted at 7ft lens height and 22ft throw distance. Screen size set to 120" diag 16:9, with the bottom at 26" from floor.

Based on this "subjective" test, the Da-lite materials matched the results already posted.

Here are some observations that differ significantly from the chart posted on the 1st page:

- Seymour XD (AT material) had 0.

- The Stewart Studiotech 130 G3 w/Microperf, and a non-perf Studiotech 100 showed 0 polarization.

- The Stewart Firehawk G3 had 100% polarization. THIS IS AN UNDERSTATEMENT. Rating the polarization of this material is on a completely different level than all of the others. On a scale of 1-4 polarization, the Firehawk G3 rates a 10 as it goes completely black.

While some other samples rated a 3.5 or 4 on the polarization scale, in horizontal testing (correct orientation for JVC) the Firehawk G3 is a nice and bright, however in the vertical test (incorrect for JVC projectors) this material went 100% BLACK. No other material came close to this extreme polarization level.
Hi,

Thanks for your observations.

So in referring to my prior post, in terms of 3D viewing the Firehawk has a distinct advantage over the Stewart Studiotech 130 G3 even if it doesn't have an advantage in 2D viewing?

Does the Firehawk's polarization performance provide an advantage in dealing with ghosting?

Thanks.

Larry
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post #126 of 310 Old 02-01-2011, 10:34 AM
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Quote:
Originally Posted by LarryChanin View Post

Does the Firehawk's polarization performance provide an advantage in dealing with ghosting?

Thanks.

Larry
NO. Ghosting has nothing to do with polarization preservation. You will get just as much (or little) ghosting on a polarization preserving screen as a non polarization preserving screen.

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post #127 of 310 Old 02-01-2011, 10:44 AM
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NO. Ghosting has nothing to do with polarization preservation. You will get just as much (or little) ghosting on a polarization preserving screen as a non polarization preserving screen.
Hi,

Thanks for the response.

I gather your response pertains to the JVC projectors, but there are other 3D projectors in which this would be an advantage?

Quote:
Originally Posted by Ron Jones View Post
Let us now consider projection screen surfaces that are suitable for use with 3D projectors that use polarization to separate the right and left images. Such screens must maintain very near to 100% of the polarization of the light being projected, otherwise crosstalk (i.e., ghosting) between the right and left images will result.
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post #128 of 310 Old 02-01-2011, 11:10 AM
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NO. Ghosting has nothing to do with polarization preservation. You will get just as much (or little) ghosting on a polarization preserving screen as a non polarization preserving screen.
Actually, in a passive, polarised system, most of the ghosting is caused by depolarised light - where the polarisation is not preserved by the screen. So the polarisation retention is very relevant to the ghosting.

This is, of course, different to the ghosting in active shutter systems.
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post #129 of 310 Old 02-01-2011, 11:21 AM
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Originally Posted by rdjam View Post
Actually, in a passive, polarised system, most of the ghosting is caused by depolarised light - where the polarisation is not preserved by the screen. So the polarisation retention is very relevant to the ghosting.
Hi,

When I watched Avatar in 3D in a commercial theater we used polarized glasses. So I presume the theater used a screen with characteristics similar to the Firehawk.

Do you know of any consumer projectors that use this technology?

Thanks.

Larry
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post #130 of 310 Old 02-01-2011, 11:31 AM
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Quote:
Originally Posted by LarryChanin View Post

Hi,

When I watched Avatar in 3D in a commercial theater we used polarized glasses. So I presume the theater used a screen with characteristics similar to the Firehawk.

Do you know of any consumer projectors that use this technology?

Thanks.

Larry

I'm not familiar with the Firehawk or how it is constructed. But the best passive 3D screens (for polarisation) are based on "silver reflective" bases. Anything else tends to break up the polarisation, even "silver" plastic.

Also, sometimes even a silver-based screen can be tripped up by the coatings which are applied to it. For instance, in my U3D thread I tested the SI Black Diamond II, which I thought would be fine. It was fine with Linear polarisation (ie IMAX) but broke up circular polarisation (RealD).

Yes - there are some passive 3D products coming to market which use polarisation. The first of the "affordable" ones is the LG 3D projector, which uses circular polarisation.

But, in the meantime, I am building two dual-projector test systems over in the "Ultimate 3D Projection System" thread linked in my sig. I will also be testing a variety of "3D" screens in that thread, using a simple test pattern I devised specifically to measure the de-polarisation, for both linear and circular outputs.

I will add the Firehawk to my tests (I had not really considered it suitable for polarised systems, so did not have it on my list). I can add any other screen materials you're interested in also.
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post #131 of 310 Old 02-01-2011, 11:34 AM
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Quote:
Originally Posted by rdjam View Post

Actually, in a passive, polarised system, most of the ghosting is caused by depolarised light - where the polarisation is not preserved by the screen. So the polarisation retention is very relevant to the ghosting.

This is, of course, different to the ghosting in active shutter systems.


That is a great point rdjam I was talking strictly active shutter as far as my comments. Passive would be a different story it sounds like.

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post #132 of 310 Old 02-01-2011, 11:36 AM
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Originally Posted by LarryChanin View Post

Hi,

Thanks for the response.

I gather your response pertains to the JVC projectors, but there are other 3D projectors in which this would be an advantage?



Larry

My experience is strictly with my RS40 and HP 2.8 (retains no polarization) and ST130 G3 (retains some polarization............rated as a 2/4 on this thread as far as the polarization rating). What little ghosting I have seen on certain discs ghosts the exact same on both screens.

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post #133 of 310 Old 02-01-2011, 01:54 PM
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Quote:
Originally Posted by Toe View Post

That is a great point rdjam I was talking strictly active shutter as far as my comments. Passive would be a different story it sounds like.

No probs, Toe

With an active shutter 3D system, such as yours, the ghosting will appear pretty much the same on all screens - the only perceived difference really only being caused by differences in brightness or CR of each screen. The ghosting seen in active shutter systems are the result of the glasses and the projector, not so much the screen.

To compare the polarisation retention of various screens, one has to have a polarised setup to throw at it. Over the next couple of weeks, I'll be doing a comparison of a few screens (in a polarised systems) to see which ones I think are the leaders, over in the U3D thread.

I'll hopefully be testing both Linear and Circular polarised setups, as I discovered there's a big difference in how some screens handle each of them. Circular is more difficult to preserve.

I'll post those results here.
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post #134 of 310 Old 02-01-2011, 02:20 PM
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Quote:
Originally Posted by rdjam View Post

Based on the title of this thread, I think it would be really good place to cover screens made for polarised projection systems using passive glasses.

I'll be getting a bunch of screen samples soon and I've designed a test pattern to test their polarisation retention.

If it's OK, I'll come back to this thread and post results over the next couple of weeks...

Quote:
Originally Posted by Ron Jones View Post

Thanks -

Once you get the results, I can update Post #1 to add the info there.

Quote:
Originally Posted by rdjam View Post

I'm not familiar with the Firehawk or how it is constructed. But the best passive 3D screens (for polarisation) are based on "silver reflective" bases. Anything else tends to break up the polarisation, even "silver" plastic.

Also, sometimes even a silver-based screen can be tripped up by the coatings which are applied to it. For instance, in my U3D thread I tested the SI Black Diamond II, which I thought would be fine. It was fine with Linear polarisation (ie IMAX) but broke up circular polarisation (RealD).

Yes - there are some passive 3D products coming to market which use polarisation. The first of the "affordable" ones is the LG 3D projector, which uses circular polarisation.

But, in the meantime, I am building two dual-projector test systems over in the "Ultimate 3D Projection System" thread linked in my sig. I will also be testing a variety of "3D" screens in that thread, using a simple test pattern I devised specifically to measure the de-polarisation, for both linear and circular outputs.

I will add the Firehawk to my tests (I had not really considered it suitable for polarised systems, so did not have it on my list). I can add any other screen materials you're interested in also.

Quote:
Originally Posted by Ron Jones View Post

If you already have a JVC projector (or any other LCD or LCoS based projector), then you will also need either a pair of 3D glasses (eg.., JVC or Xpand) -or- a polarizing filter like you would use with a camera. Using the projector display a bright static image (using pause on a disc player or DVR) then view the image by looking thru the polarizing filter or 3D glasses (see note below). Then rotate the glasses/filter 90 degree and see if the projected image gets darker or lighter. If you don't see any change in the brightness of the projected image as you rotate the glasses or filter that means the screen is not retaining polarization, but if you see any signficant dimming then the screen is retaining some of the polarization. The greater the different between the brightest and the darkest the image gets, the more of the polarization that is being retained by the screen. If the screen were to fully retain all of the polarization then with some orientation of the polarizing filter the image would appear totally black.
Note: There are two types of polarizing filters, linear and circular. You need a linear viewing filter for the above test. The 3D shutter glasses use a linear polarizing element and can be used for the above test. The passive RealD glasses you get at a movie theater use circular polarized lens and you can use these for viewing test, but you need to look at the screen thru the glasses in reverse which makes these work as a linear polarizing filter. Finally if using a camera filter, if it is a typical one from a film camera then it's probably a linear filter and can be used for the above test. If it's used with a digital camera it's probably a circular polarizing filter and in order to use it you need to view the screen while looking in the reverse direction thru the filter. If in doubt just try viewing thru one side of the filter as you rotate it, then view thru the other side of the filter as you rotate it. If you see a difference in the projected image brightness as you rotate the filter (while viewing in either direction thru the filter) then the screen is retaining polarization. If you do test your screens, please post your results on this thread.

Hi Ron,

So if I understand this correctly with the advent of the LG 3D projector which uses circular polarization, rather than linear polarization, it looks like you will be maintaining two ratings for each screen material indicating the performance for both circular and linear polarization?

Is the testing procedure for circular polarization just slightly different from the above procedure?

By the way, it might be useful to reproduce the testing procedures in the first posting.

I would also like to say how much I appreciate your efforts in establishing these threads and your helpful and knowledgeable contributions.

Larry
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post #135 of 310 Old 02-01-2011, 03:11 PM
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For my own testing I'm using a very simple 3D pattern - a series of 100% white dots are shot from the side that is NOT supposed to be seen, and they fall within a series of squares ranging from 1% white to 30% white.

First, I put the glasses directly into the light path to block the projector that should NOT be seen, and I observe the intensity of the white dots, to see which square they match. This allows me to establish a baseline, which I then know that no screen will be able to exceed, since it is the very maximum exclusion that the projector lens and glasses paired, will allow.

Then, I remove the glasses from the light path, put them on, and view the reflected light from the screen - making the same notation as to which square the reflected circles (that should not be seen) match. I can then deduct the baseline percentage from the percentage reflected from the screen, to get a rough idea of how much ghosting was due to the failure of the screen to retain polarisation.

Tho not fully scientific, it is logical.

And yes, I will have to run it twice for each screen - once using the Circular polarised setup, and once with the Linear setup. It's a pain, but I have seen screens that are OK with linear, that DEFINITELY still failed circular.
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post #136 of 310 Old 02-01-2011, 03:13 PM
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Here is an example of the custom image I threw together for the tests.

I think it comes out a bit small when uploaded here as an attachment.

Once I have all the parts I'm waiting for (couple more filters on the way, and some screens) I will be able to knock out all my testing of the screens over a couple of days, I hope..

I will have samples of 3D screens from Stewart, Dalite, Harkness and SI - most have arrived, but not all yet.

Harkness Spectral 240
SI Solar 1.3
SI BD II 1.4 (Linear tests only - not circular compatible)
Dalite 3D Virtual Gray
Dalite Silver Matte
Stewart Silver 3D
Stewart Silver 5D

If anyone has any other suggestions from other manufacturers please let me know - but the above are the only screens recommended by those manufacturers to retain passive 3D systems' polarisation.
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post #137 of 310 Old 02-01-2011, 03:15 PM - Thread Starter
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Quote:
Originally Posted by LarryChanin View Post

Hi Ron,

So if I understand this correctly with the advent of the LG 3D projector which uses circular polarization, rather than linear polarization, it looks like you will be maintaining two ratings for each screen material indicating the performance for both circular and linear polarization?

Is the testing procedure for circular polarization just slightly different from the above procedure?

By the way, it might be useful to reproduce the testing procedures in the first posting.

I would also like to say how much I appreciate your efforts in establishing these threads and your helpful and knowledgeable contributions.

Larry

I have done no testing myself for circular polarization. This geneally would be of greatest interest for screens used with projector(s) that employ right vs. left hand circular polarization as the technique to seperate the right and left images. Thus for use with thiese types of projectors, it is screens that are intended to maintain full polarization that whould need to be verfied to maintain circular and not just linear polarization. I have not tested any of these screen myself, but I suspect that Rob (rdjam) will be in the best position to test such screens for retaining circular polarization (see his earlier posts above). Once I get his results I will add that info to Post #1 of this thread.

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post #138 of 310 Old 02-01-2011, 03:55 PM
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I have done no testing myself for circular polarization. This geneally would be of greatest interest for screens used with projector(s) that employ right vs. left hand circular polarization as the technique to seperate the right and left images. Thus for use with thiese types of projectors, it is screens that are intended to maintain full polarization that whould need to be verfied to maintain circular and not just linear polarization. I have not tested any of these screen myself, but I suspect that Rob (rdjam) will be in the best position to test such screens for retaining circular polarization (see his earlier posts above). Once I get his results I will add that info to Post #1 of this thread.

Hi Ron,

Thanks for the response.

I was wondering if you have any thoughts regarding posting #123?

Thanks.

Larry
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post #139 of 310 Old 02-01-2011, 05:05 PM - Thread Starter
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Hi Ron,

Thanks for the response.

I was wondering if you have any thoughts regarding posting #123?

Thanks.

Larry

Grey screens for HT were first introduced for use with projectors that had poor contrast and with modern HT oriented projectors with good contrast ratios I feel the only reason to even consider a grey screen is if you are trying to deal with uncontrolled ambient lighting or perhaps very light colored ceiling and walls. This is consistent with what reps from Da-lite have indicated to me as recent as 2 years ago. Even in the case of a HT with ambient light issues, a grey screen may not be the best solution. Also many (but certainly not all) grey screens seem to have manufacturer's specs that overstate the actual screen gain. So I would always suggest getting samples of the screen materials you are considering so that you can do your own testing side-by-side in order to get some ideal just how bright the whites will be and how dark the blacks will be in your specific room.

If you do have ambient light issues to deal with, its my understand that the Firehawk is one of the better grey screens currently available, but for its maximum gain it has a rather limited viewing angle.

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post #140 of 310 Old 02-01-2011, 06:04 PM - Thread Starter
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Quote:
Originally Posted by coolplazma View Post

Last night I was viewing some Da-lite, Stewart, Draper and Seymour samples taped up on a wall, and then used reversed RealD glasses to compare polarization. My RS40 is mounted at 7ft lens height and 22ft throw distance. Screen size set to 120" diag 16:9, with the bottom at 26" from floor.

Based on this "subjective" test, the Da-lite materials matched the results already posted.

Here are some observations that differ significantly from the chart posted on the 1st page:

- Seymour XD (AT material) had 0.

- The Stewart Studiotech 130 G3 w/Microperf, and a non-perf Studiotech 100 showed 0 polarization.

- The Stewart Firehawk G3 had 100% polarization. THIS IS AN UNDERSTATEMENT. Rating the polarization of this material is on a completely different level than all of the others. On a scale of 1-4 polarization, the Firehawk G3 rates a 10 as it goes completely black.

While some other samples rated a 3.5 or 4 on the polarization scale, in horizontal testing (correct orientation for JVC) the Firehawk G3 is bright (meeting the 1.25 gain expectations), however in the vertical test (incorrect for JVC projectors) this material went 100% BLACK. No other material came close to this extreme polarization level.

I haven't tested any of the Stewart (or Seymour) screens and the ratings for those listed in Post #1 came from postings by other forum members. Given the significant difference in your results from those of the others I must wonder if Stewart has been making changes to how their screen surfaces are made, even for the current generation of screens (e.g., StudioTek 130 G3). Since Stewart does not specify the level of polarization that is retained (except for their silver screens specifically sold for 3D) they could change how a given screen is made without even realizing it has changed how it handles polarized light. Did you just recently receive your samples from Stewart?

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post #141 of 310 Old 02-01-2011, 09:50 PM
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Quote:
Originally Posted by coolplazma View Post

Last night I was viewing some Da-lite, Stewart, Draper and Seymour samples taped up on a wall, and then used reversed RealD glasses to compare polarization.

Thanks for the results. Did you try having 2 pairs of glasses at the same time? The reason I ask is that I think small differences can be hard to detect if not looking at two things at once. I just wonder if one of these might retained a very small amount of polarization that wasn't visible in the test. On a more recent non-perfed Studiotek 130 (probably a G3, but I would have to check I think I measured about 30% higher with the JVC glasses at the right orientation versus turned 90 degrees.
Quote:
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- The Stewart Firehawk G3 had 100% polarization. THIS IS AN UNDERSTATEMENT. Rating the polarization of this material is on a completely different level than all of the others. On a scale of 1-4 polarization, the Firehawk G3 rates a 10 as it goes completely black.

I wonder if Stewart makes a white screen with the same gain layer as this Firehawk G3, but without the gray backing. I seem to recall reading or hearing that the gain layer for the Firehawk was about 1.8 or so. Even if Stewart doesn't officially sell a white screen with the same characteristics other than the gray, I'm pretty sure they will do custom in at least some cases and might agree to make a screen identical to the Firehawk G3 except for the gray part.

This screen could help retain ANSI CR for 3D also by having reflections go out to the room and become randomly polarized before coming back to the screen, then get rejected by the glasses at a higher rate compared to the first reflections going to the glasses. The Firehawk already had 2 factors helping ANSI CR retention (gray and high gain layer), now it looks like there is a third for 3D (although I don't know if it really makes much difference at that point).

--Darin

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post #142 of 310 Old 02-03-2011, 09:03 AM
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Yes these were all new samples. The Stewarts were obtained through Mark Haflich.

Using 1 pair of reversed RealD glasses was sufficient to see minor polarization in screens such as Da-lite Da-Mat which is very slight. Also note as a sanity check, my 5 Da-lite samples all checked out with the same rating as Ron's chart. It is only the Stewarts that varied.

It was surprising to see 0 change in the ST 130 G3 Microperf, as by all prior posts this one had been rated with 2-3.

Firehawk G3 (1.25 gain)... you see the black banner at the top of this forum? that is how black it goes when I view it with the incorrect alignment. Jaw dropping. The sample I received is a deep grey color (also received it in Micoperf which appears to be the same material) and has a "silveriness" to it. I don't know if they recently changed its composition or not, but perhaps they introduced something new after their 5D testings.

I have not yet attempted to determine how these samples look for watching 3D, ie: clarity, CR, etc. which would be difficult to determine given the small swatch size.

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post #143 of 310 Old 02-04-2011, 09:11 AM - Thread Starter
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Originally Posted by coolplazma View Post

Yes these were all new samples. The Stewarts were obtained through Mark Haflich.

Using 1 pair of reversed RealD glasses was sufficient to see minor polarization in screens such as Da-lite Da-Mat which is very slight. Also note as a sanity check, my 5 Da-lite samples all checked out with the same rating as Ron's chart. It is only the Stewarts that varied.

It was surprising to see 0 change in the ST 130 G3 Microperf, as by all prior posts this one had been rated with 2-3.

Firehawk G3 (1.25 gain)... you see the black banner at the top of this forum? that is how black it goes when I view it with the incorrect alignment. Jaw dropping. The sample I received is a deep grey color (also received it in Micoperf which appears to be the same material) and has a "silveriness" to it. I don't know if they recently changed its composition or not, but perhaps they introduced something new after their 5D testings.

I have not yet attempted to determine how these samples look for watching 3D, ie: clarity, CR, etc. which would be difficult to determine given the small swatch size.

I've added your test results to the table in Post #1. I requested screen samples from Stewart more than 2 weeks ago, but I have received nothing yet.

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post #144 of 310 Old 02-05-2011, 10:38 PM
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A much simpler and cheaper solution to polarized projectors--you can just put a piece of depolarizing acrylic (see any art or plastics store or online-- but they vary so you have to experiment) in front of the lens and this eliminates the need for polarizing screens and the differences between shutter glasses making the 3DTV Corp 8 protocol Gen2 emitter and almost any kind of glasses as bright as any. Of course another solution (e.g., if there are color artefacts or other issues with the acrylic) is a piece of half wave plate-- which rotates the plane of polarized light to whatever angle you want-- thus again enabling use of many kinds of glasses with 3DTV Corp Gen2 emitter (or our midrange or cinema emitters for those with a very big venue).
There are also other screen makers with higher gain screens than those listed--see my article on Infocomm on the 3DTV page.
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post #145 of 310 Old 02-06-2011, 02:40 PM
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Confirmed my prior findings for 3D mode with the JVC RS40.

The Stewart Firehawk G3 (1.25 gain) sample works great with correctly oriented JVC (horizontal) shutter glasses, and it goes 100% black when the glasses are held vertically. There is no way you could use ExpanD x103 glasses (vertical p.) with this screen material & pj series (40/50/60).

The ST130 G3 Microperf (1.3 gain) sample remained at 0 polarization observed. Regardless, it appeared equally as bright in 3D as the Firehawk which had 100% polarization.

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post #146 of 310 Old 02-06-2011, 11:35 PM
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Here is a copy of my yet results from tonight, in relation to retention of circular polarisation for a passive 3D system, with select screen specifically designed for polarized light.

Well - started the tests a bit late, on account of da Superbowl

Good and bad results tonight. But the main summary points are: (1) circular is definitely not the way to go (2) the Solar HD 1.3 I just got from SI that was supposed to be circular compatible retains almost zero polarisation.

Also, these results are not complete, as it seems I left the Harkness sample in the office - and I neglected to run the "baseline" measurement with just the pure filters, without screen interplay, to see what the theoretical maximum retention COULD be.

I will edit this post tomorrow night with the additional numbers.

That said, here is what I found tonight. Remember, these are not precise, as they are based on eyeballing the test patterns.

In order of performance on retaining circular polarisation:

Stewart 3D - 80 to 81 %
Stewart 5D - 77%
Dalite Silver Matte - 77%
Dalite 3D Virtual Grey - 70%
SI Solar HD 1.3 - almost 0%

Overall, I am very disappointed in the performance seen in these tests. Even the very best screen in the tests barely retained more than 80% of the circular polarized light, meaning that there will always be some situations where ghosting may be an issue, no matter what you throw at it.

This would explain why RealD has to go to such technological lengths to pre-process movie material, estimate the ghosting, then cancel an appropriate amount of light from the other image. They certainly make it work well in the theaters, but that is not a realistic approach for a home theater.

The Harkness screen may still outperform the Stewart when I test it tomorrow, but it is still likely to not be able to retain a perfect score with circular.

So, while I had originally thought that circular would be the perfect solution, as it allows me to move my head more, my testing has shown me the error of my pre-conceptions.

So it is looking extremely likely that Linear polarized is the way to go.

Btw - until you have seen 3D at 48 frames per second, using frame interpolation, and flashed at 96 hz - you just cannot understand what you are missing.

I wish that I could have shown James Cameron how amazing Avatar looked on this system tonight. It was never so clear and easy to follow the movement in the theater.

The scenes where they are flying through the valleys and floating mountains were absolutely spectacular. And the action scenes just didn't break up at all, like the way they did in the theater.

And How to Train Your Dragon was amazing also. Particularly the fight scenes, such as at the beginning, where they introduce Astrid, and the huge dramatic battle with the Uber-monster at the end. The intro to the battle in the ring, where the camera is flying, circling the ring with all the people just highlights how crystal clear and smooth this system is with the FI. I promise you you've never seen anything like it.

Anyway. More results tomorrow. But I think we are now drawing close to the end of all the investigation for the ultimate system. And it looks more and more likely that Linear will win this by a longshot.

I'm hoping that the end result will be a screen that allows good 2D qualities, not just 3D. I'm holding hopes out for my trusty BD II to come through in the linear tests next weekend.
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post #147 of 310 Old 02-07-2011, 12:19 PM - Thread Starter
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Quote:
Originally Posted by rdjam View Post
Here is a copy of my yet results from tonight, in relation to retention of circular polarisation for a passive 3D system, with select screen specifically designed for polarized light.

Well - started the tests a bit late, on account of da Superbowl

Good and bad results tonight. But the main summary points are: (1) circular is definitely not the way to go (2) the Solar HD 1.3 I just got from SI that was supposed to be circular compatible retains almost zero polarisation.

Also, these results are not complete, as it seems I left the Harkness sample in the office - and I neglected to run the "baseline" measurement with just the pure filters, without screen interplay, to see what the theoretical maximum retention COULD be.

I will edit this post tomorrow night with the additional numbers.

That said, here is what I found tonight. Remember, these are not precise, as they are based on eyeballing the test patterns.

In order of performance on retaining circular polarisation:

Stewart 3D - 80 to 81 %
Stewart 5D - 77%
Dalite Silver Matte - 77%
Dalite 3D Virtual Grey - 70%
SI Solar HD 1.3 - almost 0%

Overall, I am very disappointed in the performance seen in these tests. Even the very best screen in the tests barely retained more than 80% of the circular polarized light, meaning that there will always be some situations where ghosting may be an issue, no matter what you throw at it.

This would explain why RealD has to go to such technological lengths to pre-process movie material, estimate the ghosting, then cancel an appropriate amount of light from the other image. They certainly make it work well in the theaters, but that is not a realistic approach for a home theater.

The Harkness screen may still outperform the Stewart when I test it tomorrow, but it is still likely to not be able to retain a perfect score with circular.

So, while I had originally thought that circular would be the perfect solution, as it allows me to move my head more, my testing has shown me the error of my pre-conceptions.

So it is looking extremely likely that Linear polarized is the way to go.

Btw - until you have seen 3D at 48 frames per second, using frame interpolation, and flashed at 96 hz - you just cannot understand what you are missing.

I wish that I could have shown James Cameron how amazing Avatar looked on this system tonight. It was never so clear and easy to follow the movement in the theater.

The scenes where they are flying through the valleys and floating mountains were absolutely spectacular. And the action scenes just didn't break up at all, like the way they did in the theater.

And How to Train Your Dragon was amazing also. Particularly the fight scenes, such as at the beginning, where they introduce Astrid, and the huge dramatic battle with the Uber-monster at the end. The intro to the battle in the ring, where the camera is flying, circling the ring with all the people just highlights how crystal clear and smooth this system is with the FI. I promise you you've never seen anything like it.

Anyway. More results tomorrow. But I think we are now drawing close to the end of all the investigation for the ultimate system. And it looks more and more likely that Linear will win this by a longshot.

I'm hoping that the end result will be a screen that allows good 2D qualities, not just 3D. I'm holding hopes out for my trusty BD II to come through in the linear tests next weekend.
Thanks for the circular polarization test results. I've added them to Post #1 of this thread. I'm looking forward to your linear test results.

As for Avatar and Cameron. Since he really wanted to shot it at 48Hz per eye, but Fox Studios wouldn't let him, I'm certain he would be pleased. Fox has now given him the go ahead for Avatar 2 and Avatar 3 to be shot at a higher frame rate and he is supposed to be now considering 48 vs. 60 vs. 72 Hz. Of course for the future Blu-ray 3D release of those films, we will be stuck with 1080p/24 since the Blu-ray 3D standard does not support those higher frame rates. However, I have always contended that using frame insertion for 3D really does make a lot of sense since 3D is attempting to create a virtual reality and its only the technical limitations and $$$ (and not the "director's intent") that has been limiting commercail 3D movies to 24Hz.

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post #148 of 310 Old 02-07-2011, 12:34 PM
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As for Avatar and Cameron. Since he really wanted to shot it at 48Hz per eye, but Fox Studios wouldn't let him, I'm certain he would be pleased. Fox has now given him the go ahead for Avatar 2 and Avatar 3 to be shot at a higher frame rate and he is supposed to be now considering 48 vs. 60 vs. 72 Hz. Of course for the future Blu-ray 3D release of those films, we will be stuck with 1080p/24 since the Blu-ray 3D standard does not support those higher frame rates. However, I have always contended that using frame insertion for 3D really does make a lot of sense since 3D is attempting to create a virtual reality and its only the technical limitations and $$$ (and not the "director's intent") that has been limiting commercail 3D movies to 24Hz.
I agree 100% - the proof is in the pudding with this system I've been testing for the last week. 3D fans and non-fans alike, who have viewed it over the last few days, are in love. I'm going to need inflatable mattresses, the people won't leave! lol

I think audiences are going to be blown away by Avatar 2 when they see it at the higher frame rates. Most people will never comprehend the difference until they actually see it.
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post #149 of 310 Old 02-14-2011, 12:47 PM - Thread Starter
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I added the results, to Post #1 of this thread, that were provided by rdjam (Rod) for the tests he has done for screens intended to retain linear polarization

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post #150 of 310 Old 02-14-2011, 03:27 PM
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This is my first post on the forum and given the thread topic I figured this would be the best place to ask my 3D screen related question.

I'm new to the projector game and 3D via projectors. I have recently purchased an Optoma GT720 Short Throw 3D Ready DLP Projector and have the Optoma 3D-XL on preorder to facilitate 3D via PS3, Blue Ray etc I plan on using DLP link via active shutter glasses.

I'm now actively looking for a screen for my setup and have a budget that I'm working within. In particular I'm considering going with either of these two screens:

106" EluneVision Elara II Perlux-Silver Fixed Frame Screen - 16:9 (1.4-gain, 3-ply Perlux-Silver material)

Or

106" EluneVision High Definition Cinema Grey Fixed Frame Screen - 16:9 (1.1-gain, 3-ply Cinema Gray material for high contrast and black levels)

My setup is in the basement which has ¾ (full size) windows and ambient light is fair during the day, however most of my viewing will be in the evening anyways. I will be seated 11.5 feet away and the projector is table mounted. The projector is rated at 2500 lumens with a contrast ratio of 3000: 1, however from what I have read I can expect at least a 50% drop in brightness with the projector in 3D mode and the use of the active glasses. Given that I'm unsure of what type of gain I should be looking at given the projector is fairly bright at 2500 lumens. I have decided I would like to go with a Grey / Silver screen to bump up the contrast a bit.

I'm leaning towards the 106" EluneVision Elara II Perlux-Silver Fixed Frame Screen due to the higher gain, but have concerns on the use of a silver screen with active glasses and hot spotting.

Any feedback would be appreciated.
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