3D - have 2 similar pjs, now what? - AVS Forum
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post #1 of 24 Old 01-11-2010, 11:09 AM - Thread Starter
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O.K. I have an Epson 7500 & Epson 9500 and a new lamp for each. If I want to use them in the future for 3D what do I need besides shutter glasses (or polarized glasses?)? Both projectors have lots of horizontal and vertical lens shift so stacking them and converging the images should be doable.

Somehow I need to send the signal for the left eye to one pj and the signal for the right eye to the other pj. How would this be done using a 3D BD player or a HTPC? Do I need a filter (I would guess) in front of the two projectors? The shutter glasses and the projectors need to be synced? Do I need a special screen as well?

I would think there are a number of forum members who have updated a projector and kept the previous one to use in another room or for a backup. Maybe buying 2 used projectors (same model) might be an inexpensive way to dip one's toes into the 3D ocean. Is it time to dust these projectors off?

Any ideas or thoughts would be appreciated.
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post #2 of 24 Old 01-11-2010, 11:22 AM
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It's too early to say with HDMI 1.4 being just released and how you would split the signal from a single 1.4 BD 3D player. Your best option is goint the HTPC route. I would go to the 20 000 and over forum. They have quite a few threads there about doing 3D with 2 projectors.
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post #3 of 24 Old 01-11-2010, 03:02 PM
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post #4 of 24 Old 01-11-2010, 04:50 PM - Thread Starter
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Quote:

Wow! Thanks for the help!
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post #5 of 24 Old 01-12-2010, 08:51 AM
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Quote:
Originally Posted by Deja Vu View Post

O.K. I have an Epson 7500 & Epson 9500 and a new lamp for each. If I want to use them in the future for 3D what do I need besides shutter glasses (or polarized glasses?)? Both projectors have lots of horizontal and vertical lens shift so stacking them and converging the images should be doable.

Somehow I need to send the signal for the left eye to one pj and the signal for the right eye to the other pj. How would this be done using a 3D BD player or a HTPC? Do I need a filter (I would guess) in front of the two projectors? The shutter glasses and the projectors need to be synced? Do I need a special screen as well?

I would think there are a number of forum members who have updated a projector and kept the previous one to use in another room or for a backup. Maybe buying 2 used projectors (same model) might be an inexpensive way to dip one's toes into the 3D ocean. Is it time to dust these projectors off?

Any ideas or thoughts would be appreciated.

Stacking digital projectors is quite difficult, even with all the shift ability of the ones you have. Lots of factors can come into play, such as convergence, focus, uniformity, etc...

In any event, you have both so feel free to experiement, but it may be tougher to get good results than it is worth.
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post #6 of 24 Old 01-12-2010, 10:09 AM - Thread Starter
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Quote:
Originally Posted by Jason Turk View Post

Stacking digital projectors is quite difficult, even with all the shift ability of the ones you have. Lots of factors can come into play, such as convergence, focus, uniformity, etc...

In any event, you have both so feel free to experiement, but it may be tougher to get good results than it is worth.

I agree with you Jason - good advice. I think that in a year or two there will be relatively inexpensive simpler solutions. It seems somewhat strange though that Optoma can sell a 720p 3D ready pj or $699 while the LG 3D ready 1080p pj costs $10,000! The Optoma may prove to be an nice interim solution while we wait for content and more choice of equipment.
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post #7 of 24 Old 01-12-2010, 11:11 AM
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Quote:
Originally Posted by Jason Turk View Post

Stacking digital projectors is quite difficult, even with all the shift ability of the ones you have. Lots of factors can come into play, such as convergence, focus, uniformity, etc...

In any event, you have both so feel free to experiement, but it may be tougher to get good results than it is worth.


Actually, it's very easy to get good results, the main problem right now is the lack of content, and of course the fact that you need an HTPC for this to work best.

Content is limited to either PC games (some of which look fantastic by the way) or 3d videos available from the net, none of which are big movies as of now. (they make for very nice demos though)
So, unless you're into 3d porn, the content will be very limited at least for a few more months.
Porn is one of the most widely available source of 3d, if you think about it those guys also helped VHS in that old format war, those guys are pioneers.
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post #8 of 24 Old 01-12-2010, 11:55 AM
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Originally Posted by Kamus View Post

Actually, it's very easy to get good results

As an installer and someone who has tried with with many different setups...I respectfully disagree.
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post #9 of 24 Old 01-12-2010, 12:23 PM
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You could use Infitec glasses (the ones uses in Dolby 3D theaters) and canibilize the filters for the front of the lenses. Then use another pair for viewing. A regular screen would work fine since these filters are not polarizing. Color correction is needed for perfection with a different correction for each filter. So you would really need a CMS in each projector.

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post #10 of 24 Old 01-12-2010, 02:07 PM
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Quote:
Originally Posted by mark haflich View Post

You could use Infitec glasses (the ones uses in Dolby 3D theaters) and canibilize the filters for the front of thelenses. Then use another pair for viewing. A regular screen would work fine since these filters are notpolarizing. Color correction is need for perfection with a different correction for each filter. So you would really need a CMS in each projector.

Filters from glasses are small for Epson's lens.
Infitec Dual Filter Set with Color Correction Electronics $6,081.30 (USD)

LCD projectors is more flexible than DLP's for passive 3D setup.
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post #11 of 24 Old 01-12-2010, 02:09 PM
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Quote:
Originally Posted by Jason Turk View Post

As an installer and someone who has tried with with many different setups...I respectfully disagree.

I had my setup up and running in no time at all, with really good results.
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post #12 of 24 Old 01-12-2010, 03:28 PM
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Remember you can place the filters very close to the lens surface. The image at exit of the lens glass is about the size of a chip. Put a piece of paper a half inch in front of the lens and look at the size of the image. Very small. The lenses taken from a pair of flat glasses should look fine. Stacking to get perfect pixel overlap is next to impossible but for 3D one should be able to get close enough. Remember, its really not a stack to double the brightness. Two images are flashing, so a tiny bit of displacement between each eye shouldn`t make that much difference. Am I wrong here?

I agree with Jason, that a traditional stack of two digitals to increase the brightness can`t be done without the appearance of misconvergence between the two.

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post #13 of 24 Old 01-12-2010, 03:59 PM
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Quote:
Originally Posted by mark haflich View Post

so a tiny bit of displacement between each eye shouldn`t make that much difference. Am I wrong here?

Nope, not wrong.
You just have to align them the best you can, remember: the images being displayed are different from eachother in the first place, we're not trying to focus the exact same image on a per pixel basis here.
Hell, I've even had my projectors slightly miss-aligned sometimes, and your eyes still converge perfectly for things like in-game menus that should be perfectly overlapped (even if they are slightly miss aligned, the menus converge perfectly once you put the glasses on)
That said, you should aim to converge them as best as possible to avoid eye strain.
Long story short, pixel perfect alignment is not crucial.
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post #14 of 24 Old 01-12-2010, 06:16 PM - Thread Starter
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Quote:
Originally Posted by Kamus View Post

I had my setup up and running in no time at all, with really good results.

Can you describe your set up please. No doubt you're using a HTPC with a specialized 3D video card that sends the left eye to one of the projectors from one of the computer's DVI (?) outputs and the right eye to the other projector from the computer's other DVI output. What do you use for filters and what type of screen?

Thanks for any comments and information. If this is doable and inexpensive (since the projectors are paid for) then I think there will be a substantial number of forum members willing to give this a try.
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post #15 of 24 Old 01-12-2010, 07:43 PM
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I'm using Dolby 3d glasses as filters. (and glasses) Well, i should say "used to use" since i recently sold those two projectors (sharp dt-510's), had the setup running for about 6 months though. Any kind of projectors will work, the brighter they are, the better.

I use a High Power screen, basically i just used a pair of Dolby 3d glasses as filters. they are made of glass, so heat isn't an issue. (with a polarized setup, you usually have to set them a bit far from the lens or they'll melt overtime, cause they're made of plastic)

And yes, this was on an HTPC, using a 4870 video card via IZ3d drivers (they have dual projection support)
Worked really well in lots of games. And as far as video material goes, there isn't that much out there, though i do have a few hours of footage. (no movies though)

The downside with doing it the "cheap way" like i did, is you have no color correction box, and the gamut is a bit different for each eye.
The consequence of not using color correction is, on really bright primary and secondary colors you'll see those colors brighter on one side, and dimmer on the other.
This is only on really bright colors, so on most movies and games you'll rarely see this come up, but you will every now and then.
It's not a deal breaker, but it's definitely a flaw we could do with out.
Of course if you buy everything from Infitec you shouldn't have this issue, but the price is really high if you go this route.
Last i checked it was about 2,000 for the filters (which really, is exactly the same as the glasses only a bit different shape) and about 2,000 for the correction box, not to mention Infitec branded glasses are much more expensive than the Dolby 3d ones, and from what i hear, not as good as the dolby 3d glasses.
(supposedly the dolby 3d glasses use different wave lengths that result in better color fidelity)
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post #16 of 24 Old 01-12-2010, 10:54 PM
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Quote:
Originally Posted by Deja Vu View Post

I agree with you Jason - good advice. I think that in a year or two there will be relatively inexpensive simpler solutions. It seems somewhat strange though that Optoma can sell a 720p 3D ready pj or $699 while the LG 3D ready 1080p pj costs $10,000! The Optoma may prove to be an nice interim solution while we wait for content and more choice of equipment.

that's like saying "a Kia costs around $9K, strange that a Farrari costs $200K+". You think that JUST because they both do 3D that it would be the same quality?? Why buy a Canon or a Nikon, a disposable is so much cheaper and does the same thing?
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post #17 of 24 Old 01-12-2010, 10:58 PM
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Originally Posted by Kamus View Post

I had my setup up and running in no time at all, with really good results.

you two obviously have different ideas as to whats considered "good". To you mismatched color and gamma is "good". I bet your convergence is way off too.
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post #18 of 24 Old 01-13-2010, 12:23 AM
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Originally Posted by Mikenificent1 View Post

you two obviously have different ideas as to whats considered "good". To you mismatched color and gamma is "good". I bet your convergence is way off too.

If by "good" you mean bad, then no, my convergence is not "good". my grayscale was a smooth 2.2 on both projectors @6500, the only thing off was the gamut, which as i described has a very specific side effect due to the very narrow band filters.
My projectors alignment was fine, i could get two crosshatch patterns completely aligned. (using keystone, since those particular projectors lack lens shift)

Just how do you think passive projection is even done? this isn't rocket science.
If i had gone the circular or linear polarized route my results would've been perfect, but that would've required a silver screen, all i'm doing here is sharing my results with an Infitec setup with out the color correction.
Don't jump into conclusions here with out ever having seen passive projection, this has been around forever, it's nothing new. Dual passive projection has been, for a long time the best way to do 3d stereo.
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post #19 of 24 Old 01-13-2010, 12:59 AM
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Originally Posted by Mikenificent1 View Post

You think that JUST because they both do 3D that it would be the same quality??

Huh? you actually think that a better projector would have better quality 3d stereo?
The 3d will be of the same quality if it's you're comparing it to another shutter projector, meaning... that crappy 700 buck 120hz Projector would have the same 3d effect as any other 120hz projector. (comparing shutter to shutter techniques here obviously)
Of course the picture quality and calibrated brightness would be very different on a high end one, but not the 3d itself.

The fact is, 3d for DLP's is going to be a joke to implement if they go the shutter glasses route.
This isn't as big an engineering challenge as a lot of people think, at least not for DLP+Shutter, that if TI wanted would've had 120hz+ chips out years ago for HT.
I don't know if the same can be said for LCD's or LCoS, since those panels aren't as fast as DLP, but i'm willing to bet that their 2010 panels will do 120 or 240 Hz since it's the cheapest way, and yields very good PQ.

Shutter glasses+high refresh rate will give you really high quality 3d, the only real challenge for that 3d stereo setup is brightness, and the fact that some people may find 120Hz (60 Hz per eye) not to be enough for them. (which is why a lot of makers are aiming for 240 Hz right of the bat, among other reasons)
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post #20 of 24 Old 01-13-2010, 09:02 AM - Thread Starter
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Quote:
Originally Posted by Kamus View Post

I'm using Dolby 3d glasses as filters. (and glasses) Well, i should say "used to use" since i recently sold those two projectors (sharp dt-510's), had the setup running for about 6 months though. Any kind of projectors will work, the brighter they are, the better.

I use a High Power screen, basically i just used a pair of Dolby 3d glasses as filters. they are made of glass, so heat isn't an issue. (with a polarized setup, you usually have to set them a bit far from the lens or they'll melt overtime, cause they're made of plastic)

And yes, this was on an HTPC, using a 4870 video card via IZ3d drivers (they have dual projection support)
Worked really well in lots of games. And as far as video material goes, there isn't that much out there, though i do have a few hours of footage. (no movies though)

The downside with doing it the "cheap way" like i did, is you have no color correction box, and the gamut is a bit different for each eye.
The consequence of not using color correction is, on really bright primary and secondary colors you'll see those colors brighter on one side, and dimmer on the other.
This is only on really bright colors, so on most movies and games you'll rarely see this come up, but you will every now and then.
It's not a deal breaker, but it's definitely a flaw we could do with out.
Of course if you buy everything from Infitec you shouldn't have this issue, but the price is really high if you go this route.
Last i checked it was about 2,000 for the filters (which really, is exactly the same as the glasses only a bit different shape) and about 2,000 for the correction box, not to mention Infitec branded glasses are much more expensive than the Dolby 3d ones, and from what i hear, not as good as the dolby 3d glasses.
(supposedly the dolby 3d glasses use different wave lengths that result in better color fidelity)

This sounds interesting - thanks very much. Can you tell me approximately the cost to do this taking into account that I have the projectors and screen and so I'll need five pairs of glasses, video card,drivers etc.
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post #21 of 24 Old 01-13-2010, 11:27 AM
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the video card can be any ATi or nVidia of your choice, you can not use nvidia's 3dvision drivers though, third party drivers like IZ3d is what you should use for passive projection.
the dolby 3d glasses are about 26-30 bucks each. if you go linear or circular polarizers those are much cheaper, and so are the filters (about a buck for each pair of galsses, and about 3 for each filter, and you won't have the color issues) but you need a silver screen, these vary a lot in price, and some aren't very good for 2d viewing.
The videocard only needs to be a good one if you plan on gaming, for video (that there isn't much out there off anyway) you'll be fine with out spending too much on one.
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post #22 of 24 Old 01-13-2010, 06:12 PM - Thread Starter
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Quote:
Originally Posted by Kamus View Post

the video card can be any ATi or nVidia of your choice, you can not use nvidia's 3dvision drivers though, third party drivers like IZ3d is what you should use for passive projection.
the dolby 3d glasses are about 26-30 bucks each. if you go linear or circular polarizers those are much cheaper, and so are the filters (about a buck for each pair of galsses, and about 3 for each filter, and you won't have the color issues) but you need a silver screen, these vary a lot in price, and some aren't very good for 2d viewing.
The videocard only needs to be a good one if you plan on gaming, for video (that there isn't much out there off anyway) you'll be fine with out spending too much on one.

Thanks for this. A great help!
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post #23 of 24 Old 01-16-2010, 09:24 AM - Thread Starter
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I thought I'd bump this since some of the other 3D threads touch on this topic and Kamus's posts here.
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post #24 of 24 Old 01-17-2010, 12:38 PM
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Two things against Dolby...light you need quite a bit more since it is only 10% efficient as compared to 15-28% efficient on the Polarized systems. Steve Guttag from http://www.film-tech.com/
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