The Ultimate 3D projection system: A Practical Discussion Thread - Page 66

My questions are:

1) StereoBright filters = PAR ?
because then I get the most of the light - simply rotate all the light +/-45 deg with a Half-Wave-Retarder on all spectrum (when using 3LCD projector, the green channel must be crossed between L and R image)

2) when the SPAR filters work like you described - rotation of only green channel - then how accurate is the selective HWR only for green wavelengths, because BlackShark described some color distortion in the corners (if I can recall it correctly)

3) question above raises the following: what is easier to achieve - a selective green-only HWR or full spectrum HWR?

4) and again: why are PAR filters 20% brighter than SPAR?

5) does the (S)PAR filters have as the last layer a linear filter with the same orientation like the rotation of the HWR? or is it pointless because the light was linearly polarized already in the projector?

(4+5: perhaps SPAR filters have final linear filter and PAR do not. That could explain more light throughput as well as higher ghosting reported by users...)

Sorry for being too curious

a wave plate half / full or quarter will not just change the angle of a linear polarizer by a fixed angle, it turns it into a spiral. ill have to think about the other questions a bit..

now I can see that my picture is (partially) wrong.
I have to think about the spiral as you wrote as well, I thought until now that HWR rotates the polarization plain...

New developments.

I am putting up a new home theater for basement.

came across this option:
epson w16sk

http://www.epson.com/cgi-bin/Store/jsp/Product.do?BV_UseBVCookie=yes&sku=V11H494020&cookies=no#2

what do you guys think?
granted it is not 1080p -- but could it still be used

I was thinking of using silver lite 2.5 from da-lite

WHAT is the best screen as of now for passive 3d and 2 D viewing.
If answer is harkness 240, how would i get motorised 144 to 150 inch version??

thanks in advance for any responses

I am really sure you will not get a motorized Harkness. If you want motorized I highly recommend going with motorman's passive solution and just getting two bright 1080p projectors and forgetting polarized. I really can't imagine a silverized screen standing up to repeated unrolling cycles. I could be wrong of course.
If I was going passive polarized I would go with a fixed curved Vutec Silverstar 3D-P screen and 2 Epson 3010 projectors. My 5010 has all colors at the same angle so a simple half wave plate would give me polarized with little loss. I assume the 3010 is aligned the same way. Haven't seen a review of the Silverstar passive screen yet, but based on how magic my old silverstar is that is the only screen I would buy without a review.

how can i be so foolish? :-)).
makes me feel like a rookie which i am!!

so silver screen will be fixed and if needed , i can have a white matte screen roll down in front of it for 2d movies.

Or is the silver screen ( vutech) good enough for 2d Also??[/B]--

any comments on the new stackable epson 3d passive projector i mentioned and linked above -- sounds like awesome deal under 2000 bucks-- but max resolution is wxga

@ Zorg

1 - What are these PAR filters ? I only know standard polarising ones and the SPAR ones.
2 - SPAR filters rotate all 3 channels : it rotates one channel by 45° and the other 2 by 135 ° (they start horizontal and vertical, the end all 3 at 45°)
3 - I don't know
4 - Advisol's spar filters claim 65% transmission. I have their earlier model which claim up to 80% transmission, however the colour balance is affected by the angle of the beam : they don't like short throws. On my 1.7 throw ratio, a purple colour shift is visible on the edges of the picture. (omega has the same problem except their shift is blue)
I read somewhere that their newer filters correct this effect at the expense of transmission, however I haven't seen anyone who tested them confirm this.
5 - Yes. Anyway you should always add a linear filter after rotating the polarisation to make sure the picture is as clean as possible. The internal polarisation of projectors isn't perfect and neither are retarders. If you don't add a linear polariser you will add unnecessary crosstalk.

@ drlushan

The Harkness Spectral 240 (which I have) is a good 3D screen and it would be a good enough 2D screen as long as the audience is sitting far enough from it. In a home though, it is disappointing for 2D due to it's very visible sparkling grainy texture. I do not recommend this screen for 2D viewing if you are sitting at less than 5 metres or for 3D at less than 3 metres. (distance starting from which the texture starts to dissolve into the picture, but you need a little bit more for the texture to become invisible)
Overall it isn't a bad screen, especially considering the polarisation extinction ratio at that price and the manufacturer's openness to sell you only the screen material without frame, but it is far from perfect in the home.
Edited by BlackShark - 1/28/13 at 10:34pm

I would try:
http://strong-mdicinema.com/products/screens/mdi-stereoview-3d/
I have a sample they sent me and it appears to be really nice and very reasonably priced.

@ Blackshark:
Thanks for answering
In the meanwhile I got answer from Advisol:
1) their StereoBright filters, which are designed for 3LCD projectors with green orthogonal to red+blue, are selling only directly, not by the dealers. There is a presentation explaining stereobrigt, the green channel must be swapped between L and R. The filters are basically HWR with no linear filter at the end, because of the 3LCD.
Perhaps it could work with JVC's dila with the linear filter to deminish ghosting, but I don't know, this must be further determined.
2) they confirmed, that SPAR rotates selective green and red+blue (which is awesome), linear filter is present at the end, 5) explainted too. They confirmed color nonuniformity as well as color distortion, but they did their best.
4) don't know yet for sure, but I guess they needn't use the selective rotation (as DILA are polarized uniformly), so perhaps its brighter..

Look at the offer from UMA service (former Silverfabric) http://www.uma-services.de/wp-content/pdf-download/8_SF-Polarizer_Systems_April_2012.pdf at the end the PAR filters for JVC. I guess it is brighter because the filters needn't be so complex as the dila have uniformly polarized output. And perhaps there is a linear polarizer at the end because of that which causes better separation. So maybe thats why rdjam reported as awesome; little to no crosstalk between L/R.
Edited by zorg43x - 1/29/13 at 3:16pm

Someone on the Optoma 3DXL forum claimed the Optoma HD33 projector has 3DXL functionality built in. That is a pretty huge thing if it works right, and since the same company makes the 3DXL there is no reason why not. That knocks off a lot of money and complexity to a dual passive system. If they only polarized the the colors the same way it would be really awesome. **oops, that is a dlp projector. No polarization.
Edited by wnielsenbb - 1/29/13 at 3:34pm

I don't know what you wanted to say with your last sentence though, but we are talking about a PASSIVE way and two independent light sources, for left and right eye separately. HD33 uses RF shutter glasses as far as I know so the light flickers between both eyes. And the last thing about this projector would be the 3x speed colour wheel per frame in 3D, which I guess would be quite rainbow-concerning for my eyes...

The HD 33 also supports left/right projector usage if you have two.
from optoma "As a full 1080p, it supports all 1080 p formats natively without needing an Optoma 3D-XL box converter box"
http://www.optomausa.com/products/detail/HD33

So two of these and motormans filters and you are ready to go. The only issue is limited placement flexibility and mostly no lens shift. rainbows do suck.

As far as I know this only means there is no need to use the 3DXL to convert HDMI 1.3 and lower signals into 1.4. The HD33 does not do EVERYTHING the 3DXL does, and in this case the missing link is how the 3DXL pair separates left image from right image to split to two projectors. I do not believe the HD33 can be set to only "look at" left eye or right eye info on it's HDMI connector.
SORRY, I stand corrected, it does allow you to set just left eye or right eye, cool!

yeah, it would be really awesome if it had lens shift, or at least a complementary version with a slightly different projection angle.

I have the Optoma GT720 and it has a ton of vertical image shift (digital), but I believe that is because those "720p" DLP projectors actually use 1280x800 DLP chips, and the extra 80 pixels of unused image height are used for shift. I doubt that is the case with a 1080p chip however, but still there may be some shift possible via the menus...

Nice! I didn't know that. Maybe that's why they discontinued the 3D-XL! But when you don't want to stick to optoma projectors, the next alternative is the VIP3D evolver for $1000 which is more than double the price of two 3dxls or let's see how things work out with cheaper versions of geobox..

thanks blackshark for your response above.

so then , what will be best screen for home use.
i am trying 130 to 150 inch screen
2 rows of seating-- first row about 11-12 feet.

which screen is the most reasonable for passive 3d ( and should be good for 2 D also)for the money paid--what is your recommendation?
1) stewart 5d
2) da-lite silver lite 2.5
3) vutec silverscreen 3dp
4) 3djam seems to be using blackdiamond 2.7


the other huge question is,

which projector in the 1000 dollar to 2000 dollar range price ( each--total would be twice) -- is best suited for passive 3d with geobox or 3dxl.

and then last but not least
if each projector has filters mounted in front of it--- what do you all do when you want to watch 2d--. 80 % of my use will still be in 2d. so screen and projector should be able to switch to 2d without manual removal of filters etc, is only one projector on or are both projectors on when you watch 2d? how do you control which projector is on??--how do you guys switch and do you get good results with 2d

thanks in advance

i think you should get the silverstar so you can tell me how it goes. The big advantage is the curved screen which should make it much more acceptable for 2d. I would stretch the budget and go with the Epson 5020 for the simple halfwave plate almost full light polarization. I bet the cheaper 3020 is aligned the same way which would save some money, but without lens shift you would have to use a tiny bit of digital shift. I am sure it would be fine. Since you wouldn't be losing light from the plate you could just turn one projector on and it would look normal. Someone posted in here what they do is tape a paper flap next to the ir receiver on each projector so when they want just one on they point the remote at the wall on that side of the room. Just use them evenly to keep bulb life the same. I don't have a passive setup yet myself. Well I have half of it. I have a harkness 3d screen, one 3D-XL and one 5010. Just need another 3D-XL and 5010 and the half wave plate retarders. I really don't like the Harkness since I like to sit close and the screen grain is nasty, so I would probably get the Silverstar too.

how much light do you think would aditional linear filter after the halfwave retarder take away? in the same orientation like the rotated light by the hwr (+/-45 deg. i assume) because i guess with only hwr there would be bigger crosstalk, wouldn't it?


just my opinions:

i'm with those epsons too because of the same polarization plane for all colors. and I definitely recommend lensh shift, my projectors have it and i cant' imagine to work without it (so that means 5010, although over 2000 ansi lm is a bit too much for me even on 3d but on silver screen...). motorized lens shift on some panasonic i tried is really kickass, you can shift almost the whole screen size in all directions.

about the tape my sanyo can be switched on on the projector is a button so no need for a tape :P
anyway, i would take away the filters to save them when there's no need to burn them. and i would switch between the projectors - each time 2D choose the other projector to have the lamps around the same fatique..

Of course you want to add a linear filter after the retarder, but it's loss should be minimal. Oh, good point about the filters life. I think I would probably just use a different projector for 2D, probably an LCOS projector with lower lumens. I mount my projectors high so I would need a ladder handy to push the button manually.

so after 5 days of research including some of the above help , i am starting to reach some decisions.

Please tell me if there is something wrong in my conclusions:

1) passive 3d with linear polarization remains best option for best picture quality right now( as opposed to circular polarization, optoma system colour manipulation, active to passive electronic filters etc)

2) i am thnking to settle on geobox 501 with 2 projectors ( i am not sure how easy it will be to control, calibrate 2 X3dxl)

3) the new benq 1070 dlp projector with 10 degree vertical shift --look like an awesome deal--will get 2 of those.

4) for 3d put harkness 240 on wall in some way ( 160 inches diagonal) and in front of it will have white matte from dalite (motorised electrol cosmopoliton) drop down for 2d viewing( hope zoom on projectors will not be affected much by a couple inches distance between the 2 screens--can someone please comment on this!!!)

5) what are the best linear polarizing filters--does someone sell them so that they are easy to mount or remove.

thanks again for anyones help

I can't answer that. I haven't tested any other screen, so I don't know how their screen surface look like.
I don't know the most recent projector models, have a look online at projector reviews to find out which projector are the most interesting at the moment.
This price range corresponds to the entry/mid range market transition. The projectors will have basic features with a few extras, you won't get all the cool projector features at the same time so you'll have to choose the projector depending on what features you want most.
Are you ok with keystone correction or do you prefer lens-shift image offsetting ? How much horizontal and vertical lens shift you need : will your projectors be centred in front of the screen or will they be slightly off axis (ceiling mount or on a shelf ?), check the manufacturer's specs to see where you'll need to position the projectors in your room. What throw ratios can the projectors achieve ? You'll want to have the projector as far back in the room as possible to reduce the hotspotting and reduce the colour shift at the edges of the filter. (the colour shifts happen regardless of the type of filter you have, it's just the intensity and patterns that differ). Projectors equipped with zoom lenses loose brightness at longer throw ratio (it's due to how zoom lenses work).

How many Lumen are required ? 150 inch is quite a big screen. Mine is 106", the projectors I have are rated at 1800lumen but actually deliver 1200-1600 lumen depending on the reviews, they were plenty bright when they were new, but now that the lamps get old, I have to set them to max brightness to get a bright picture) You will need a lot of photons to keep that picture bright over time (remember lamps loose half of their brightness over time). You might consider a high lumen home projector (<2500 lumen), and you'll need to check projector reviews to make sure these projectors deliver some serious lumens and don't grossly over-estimate their lumen output. You'll also want them to give good quality pictures at their max brightness modes (most projectors have to be set at lower lamp brightness modes to provide good colour).
The type of filters will also have a great effect on the lumen loss. If you choose LCD projectors, you'll have to decide whether to buy cheap simple polarising filters which throw away half of the light or choose more expensive ones to try and save as much light as possible (it depends on your budget). If you choose a DLP projector, you'll loose half the brightness regardless of the filters you choose.

At one point I considered replacing my Epson projectors with the Panasonic PT-AR100U (PT-AH1000E in europe), I figured out that these projectors would be have the most lumen within my budget while keeping the precious lens shift I really want, but replacing the projectors is quite an expensive endeavour, so I'll use my Epsons as long as possible and change them when they're really dead.
I usually don't watch 2D content on my projector but in the rare cases I do, I just clone the outputs from my computer (projectors connected directly to the PC), and turn on or off one of the projectors manually. (stepping on a chair may be required depending on how high the projectors are in the room, in my case, I can reach the lower projector in the stack directly but have to use a chair for the higher one)
Edited by BlackShark - 1/31/13 at 7:06am

I think Blackshark and I are both recommending NOT getting the harkness. My recommendations for the Epson 5020 or 3020 is in fact because being able to use half plate retarders instead of losing half your brightness to the linear filter will in effect make it like 2 times brighter than the benq. Now the benq is very cheap, and has just enough lens shift to be great for stacking, where the 3020 has none. Almost like they planned it to be stacked. However if you are going to compromise on your projector for money's sake I would just go with the Omega 3D system and keep a single screen. I am very tempted by that proposition myself. You really need to drop your screen size if you are doing this though. I would go 120" at most.

I agree, the Harkness spoectral 240 is not a good choice for 2D considering how close the viewers will sit.

I would also not recommend the Omega solution because of the size of the glasses. The glass portion of the omega glasses is much smaller than your typical polarised glasses.
Your front row viewers will be too close to the screen (12 feet for a 150" screen), the screen fill such a big field of view that I believe the screen is bigger than what the Omega glasses allow. Viewers will be able to see the edges of the glasses and I'm afraid it might result in an uncomfortable claustrophobic feeling.
I also notice a strong colour shift in the glasses near the edges of the glasses. It's a really small area in the corner of the classes, in my case the screen doesn't fill the entire field of view so the picture doesn't reach this area unless I turn the head. With your first row's field of view, this glass colour shift might be visible all the time.
Edited by BlackShark - 1/31/13 at 9:22am

You don't need the silver screen if you use the omega system,
unless you are planning to switch back and forth between your ghosting polarizer system, or your grainy hot spot 2D silver screen.
There has to be some common ground, I am not choosing sides but mixing apples and oranges and trying to integrate all these systems doesn't bode well for anyone.

thank you all so much.
your opinions and expertise matter a lot.

i am now thinking to increase the budget a bit and rearrange a bit/

1) passive 3d system with source to 2 X 3dxl-- 2 projectors
2) epson 5020 X 2 ))
3)i understood liner polarizer concept, but halfplate retarder floors me-- can you please link to exact retardar and polarizer that you would suggest.
4) screen-- you all gotta help me out. sounds like harkness is out--- what do i do then? i will drop size to 144 ( i am willing to project a smaller image on a larger screen later if it is uncomfortable). i am also willing to have a motorized matte white screen on top of a fixed wall silver screen depending on the price --- please , please give suggestions. I have contemplated vutec silver screen, blackdiamond 2.7, silver-lite 2.5--but i really need good 2d results also.
5 i am planning ceiling mount-- any suggestions on that is also welcome( will need to figure out how to mount retardars/filters in front
thanks again everyone who responds

The Blackdiamond is the only 3D screen I know has good reviews for 2D. Personally I would take a chance on the Vutec Silverstar 3D-P, but that is a big chance.
Another advantage of dual 3D-XL's is they each have 2 inputs, so you can plug dual outputs from your computer into each to do gaming in 1080p.
The retarder thing is how RDJAM went. Start at page one of this thread for more info It all sounds like magic to me. Basically the retarder turns the polarization angle of the light, so you can turn the horizontal polarization of one 5020 to 45 degrees to match the right lens of the glasses and the other one the other way to match the left lens. they don't filter out light like normal polarizers, just change it's direction. You want to run regular polarizers to clean up any stray light, but there shouldn't be too much. http://www.polarization.com/ has really cheap stuff to play with.

A plarization retarder or quarter wave plate will turn a liniar polarized image into circualr, Not simply rotate it by some fixed angle. a half wave plate dose almost nothing as it rotates a plane 180 deg to being liniar again in the same direction. one has to image a spiral of light to understand what circualr polarization is. there is a big range of plastic polarizers one can play with but some are better than others. the people who make filters and glasses have done a lot of work to pick the right materials. circualr polarizing is a good technolgy but will have some ghosting depending on ones setup.

What type of filter could be used to just rotate the polarisation angle : start with 0° linear polarisation, end up with 45° linear polarisation or 90° linear polarisation with minimal loss ?
I believe Silverfabric makes some of these which they say are for LCoS projectors, but they are expensive, almost as expensive as SPAR filters.

That would be a pair of quarter-wave retarders. The first converts to circular and the second converts back to linear, however, the fast and slow axes of the second will be rotated relative to the first depending on what shift in linear polarization angle you want. Since these are clear filters, very little loss is involved. It becomes more complicated if you want to shift just one color and the retarders need to be made with that in mind.