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Stacking 2JVC projectors

post #1 of 27
Thread Starter 
If someone was going to stack to jvc projectors, would the contrast stay the same or would it increase? In instance, if you closed the iris down on two RS66s and get 100,000:1 on both, would it increase or stay at 100,000:1?

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post #2 of 27
good question. i'd think it'd stay the same, as you'd get double the brightness in both the whites and the blacks

depending your room though, you might notice the increase in whites more than the increase in blacks.
post #3 of 27
Thread Starter 
I assume just brightness too
post #4 of 27
Contrast would stay the same but black level would increase. You're doubling the light output throughout the whole spectrum. For instance, if you were getting .001 ftl at 0IRE and 25ftl at 100IRE with just one projector, when adding another (assuming it's outputting the same exact amount of light and everything else is the same) you are going to double the light a 0 and 100 IRE. So now you're at .002 and 50ftl at 0 and 100 IRE respectively. Real world results will vary obviously.
post #5 of 27
Thread Starter 
Sounds about right. A dual jvc projector setup would be killer on an AT screen, where you can get about 1600 lumens calibrated at 60,000:1 with the iris open on two rs66s. Probably cost about $12K with b-stock projectors. Finding two good one, lined up correctly would be a pain
post #6 of 27
Aligning two projectors is essentially impossible, you'd need something like the Geobox discussed in the Omega 3D thread to align everything.
post #7 of 27
Quote:
Originally Posted by Seegs108 View Post

Contrast would stay the same but black level would increase. You're doubling the light output throughout the whole spectrum. For instance, if you were getting .001 ftl at 0IRE and 25ftl at 100IRE with just one projector, when adding another (assuming it's outputting the same exact amount of light and everything else is the same) you are going to double the light a 0 and 100 IRE. So now you're at .002 and 50ftl at 0 and 100 IRE respectively. Real world results will vary obviously.

Correct. smile.gif

Also hard to get perfectly aligned.
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post #8 of 27
Thread Starter 
I guess, that's why HP screens are made
post #9 of 27
I remember some guys used to stack those Sony G-90 CRT projectors to double the light output. I think I recall one guy who did it on the Forum (Art?) had some big-shot calibrator there for a week getting those two titanic tanks with six 9 inch guns perfectly aligned. tongue.gif
post #10 of 27
Thread Starter 
That member lives close by me, about 25min. I saw his and its nice.
post #11 of 27
Quote:
Originally Posted by archiguy View Post

I remember some guys used to stack those Sony G-90 CRT projectors to double the light output. I think I recall one guy who did it on the Forum (Art?) had some big-shot calibrator there for a week getting those two titanic tanks with six 9 inch guns perfectly aligned. tongue.gif

There's a big difference between CRTs and Digital Projectors, with a CRT you can (and I'm going to kill the terminology here) adjust the guns/geometry such that you can get two machines perfectly aligned. You can push/pull a portion of the frame (corner, side, etc) essentially independently of each other. This is necessary since no two machine have exactly the same optics/construction/alignment.

With a digital projector you don't have that option, the overall geometry of the output is fixed, you can zoom/shift the image, but it's all proportional across the picture. That means you need to resort to electronics, like here:
http://www.youtube.com/watch?v=yLqkZ45AW-c
post #12 of 27
post #13 of 27
Been wondering how a quad blend would go, 4 x X35 JVC's would give one 4k with brightness and CR....at a decent price.
post #14 of 27
Thread Starter 
Quote:

It seem as if they did it without much effort
post #15 of 27
Hi,

yes, it seems. With the lens-shift of these JVC and the focus setting, it seems "easy" and the result is quite amazing, isn't it ? :

One Projector :



Two Projectors :


Edited by Thebes - 7/4/13 at 5:41am
post #16 of 27
Thread Starter 
It looks pretty good. It will bring amazing results if done right. I can imaging getting getting 2 b-stock RS65 or 66s and getting 60K:1 contrast with 15ftL+ on a 165in unity screen. Can probably be done under $10K. How sharp would two eshift images be? I wonder how much you would have to pay to get a performance like that with one projector?
Edited by blee0120 - 7/4/13 at 2:32am
post #17 of 27
you should check out the Ultimate 3D thread, he had two RS40's stacked for passive 3D.
post #18 of 27
Quote:
Originally Posted by blee0120 View Post

It seem as if they did it without much effort

that's impressive and looked relatively straight forward to set up. The best part is getting to keep your existing screen and active shutter glasses. Swapping out an existing screen for a silver screen or one with high retention of polarization isn't likely in most folks agenda for a passive system unless they are head over heels for 3D or have a large viewing audience requiring cheap glasses.

The 2.8HP goes a long way to prevent needing a setup like this. The Sharp 30K @ near eye level on my screen is plenty bright in 3D.
post #19 of 27
I'd like to see some close ups of a grid pattern. Hard to make a judgement on how well two 1920x1080 projectors are aligned based on a 600x338 picture on the web.

And remember you have to be aligned a lot better for 2D (without glasses) than you do for 3D (with glasses).
post #20 of 27
Thread Starter 
Quote:
Originally Posted by zombie10k View Post

that's impressive and looked relatively straight forward to set up. The best part is getting to keep your existing screen and active shutter glasses. Swapping out an existing screen for a silver screen or one with high retention of polarization isn't likely in most folks agenda for a passive system unless they are head over heels for 3D or have a large viewing audience requiring cheap glasses.

The 2.8HP goes a long way to prevent needing a setup like this. The Sharp 30K @ near eye level on my screen is plenty bright in 3D.

The HP screen is almost the perfect match, but it can cripple speaker placement. Some like to have the theater experience with audio too.
post #21 of 27
Quote:
Originally Posted by blee0120 View Post

The HP screen is almost the perfect match, but it can cripple speaker placement. Some like to have the theater experience with audio too.

I don't think it's all doom unless you have an AT rig. With my current setup, my full range front speakers are quite large (~5 feet) with a nice size center channel. The sound stage in the front with the XT32 tuning sounds great.

visually it would be nice to just see the screen. But I'm not giving up the big HP just yet.
post #22 of 27
Quote:
Originally Posted by stanger89 View Post

I'd like to see some close ups of a grid pattern. Hard to make a judgement on how well two 1920x1080 projectors are aligned based on a 600x338 picture on the web.

And remember you have to be aligned a lot better for 2D (without glasses) than you do for 3D (with glasses).

you can see the image is a bit softer in the closeup of the 'FOCUS' screen.

Calibrating this dual projector setup might be a little tricky. smile.gif
post #23 of 27
Thread Starter 
Quote:
Originally Posted by zombie10k View Post

you can see the image is a bit softer in the closeup of the 'FOCUS' screen.

Calibrating this dual projector setup might be a little tricky. smile.gif

Calibrating would be extremely tricky I think. But laser projectors would be the ideal setup because an external device can be added to add extra lumens. But until those are available and at a reasonable price, there will be a good wait
post #24 of 27
You calibrate each one separately either if you are doing a stack or a blend.
post #25 of 27
Quote:
Originally Posted by zombie10k View Post

you can see the image is a bit softer in the closeup of the 'FOCUS' screen.

Calibrating this dual projector setup might be a little tricky. smile.gif

That's what I thought, but the translated note for that picture sounded like it was saying the other projector was blanked out when you do that, but now that I think about it, that doesn't make sense (unless they physically blocked the other projector).
post #26 of 27
In order to have both warmed up the same, the procedure is to block the light from one while you calibrate the other. Because the pixels can't be perfectly aligned, the image will look softer close up. The color temperature of a stack should hower be very close to the maximum deviation of the worst one.
Edited by mark haflich - 7/4/13 at 8:10pm
post #27 of 27
Seems like if you needed a super bright image with one of these JVC projectors you'd be better off - both monetarily and from an image sharpness standpoint - cranking the iris wide open, turning the projector up to the "high" setting, and resigning yourself to replacing the lamp every 1000 hours.
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