Do people double stack for brightness anymore? - AVS Forum
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post #1 of 17 Old 08-06-2012, 01:56 AM - Thread Starter
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I remember it was common enough with CRT projectors to coin a term for it here. Digital projection was advancing by leaps and bounds for a while, but it seems to have stopped short of high brightness with good CR.

DLP has the brightness, but even "ultra high contrast" is ~5,000:1 and a lot of brightness is sacrificed to get that. Otherwise it's ~2,000:1. And it seems the brightest models don't offer 3D, which is where the brightness is needed most.

JVC (and Sony) have the CR, but not the brightness for a large screen. I also wonder if they had the brightness, would the current optics hold up when projecting an image larger than the designers intended?

Has anyone tried double stacking recent projectors from JVC, like a pair of rs40's for high contrast and high brightness?

 

 

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post #2 of 17 Old 08-06-2012, 09:36 AM
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Unfortunately it is MUCH more difficult with digital machines. It has been done, but usually the cons outweigh the pros.

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post #3 of 17 Old 08-07-2012, 09:13 AM
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Originally Posted by AV Science Sales 3 View Post

Unfortunately it is MUCH more difficult with digital machines.
I'm curious as to "why". Is it simply that CRT projection, being analog, has (in theory anyway) infinite adjustability vs. digital?
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post #4 of 17 Old 08-07-2012, 10:40 AM
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JVC has enough brightness for a large screen if you get some gain (depending on how large we are talking). Actually the JVC is brighter than most DLP's in best mode, unless we are talking DLP's with much worse black levels.

Why do people not often do this?
Well there are a few that are doing it mainly for 3D, but I'm not convinced. My reasoning is because you can just get a brighter model projector or buy two DIFFERENT non-stacked projectors instead of stacking two of the same. With two different projectors you get different Pro's/Con's making for a more solid overall experience. For instance, the Epson 5010 and Benq w7000 both have a 1500 lumens mode and both do better in 3D than a JVC. Even if you do not care about 3D, there are 2D advantages to owning more than one model. As good as the JVC is in many movies in 2D on Blurays, there are still 2D weaknesses to its image depending on the content. I can find some movies I still would rather watch on a DLP (not that many though), but for poorer sources, TV, or some stuff, certain DLP's are just going to process things better than the JVC anyways. The JVC needs a well-filmed Bluray that was mastered correctly to look its best, but when you feed it that, it does look spectacular.

So owning two of the same model seems like a huge waste of money to get stuck with the same Pro's/Con's. So the gain in brightness you get from double stacking you can just buy a secondary projector that is brighter for when you need that extra brightness. With stacking, you have color matching accuracy issues, convergence matching, and brightness variations between the two units which will further degrade the image over time. You also are burning two lamps instead of one at a time. You mise well just put the "stacking" budgets to buying many extra lamps and use new lamps more often providing extra brightness.


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post #5 of 17 Old 08-07-2012, 04:02 PM
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Quote:
Originally Posted by Laserfan View Post

I'm curious as to "why". Is it simply that CRT projection, being analog, has (in theory anyway) infinite adjustability vs. digital?

Well I'll take a swing at that.

With a CRT you can adjust the picture size/shape basically however you want, you can pull a corner in a bit, or push it out, so you've got a lot of degrees of freedom when it comes to lining up the two images.

When you get to a digital, there's only at most three degrees of freedom (often less). The main one is zoom, to adjust the size, the other is vertical shift, to shift it up and down, and then horizontal shift but that's somewhat rare. But these are all global adjustments. So if you get three corners/sides lined up with a digital and the fourth isn't, you're sorta stuck, or at best you have to remount it to fix it.

As far as coderguy's comments, I didn't think we were talking about 3D brightness, I thought we were talking about brightness in general, like you've got a really big screen and need 1600 Lumens. If you want good contrast, two RS45s sound a lot more appealing (price wise) than a Lumis to get that brightness and contrast performance.

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post #6 of 17 Old 08-07-2012, 06:06 PM
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My comments applied to 2D as well, again you are burning 2 lamps at the same time, you will have a softer image, and as the lamps age at different rates you will limit the usefulness due to increasing brightness unevenly on the overlap. Since the convergence won't be perfectly aligned, whichever projector ends up putting out the brighter image is going to stick out which will force you to lower the IRIS settings anyhow. It also doesn't make sense because due to lamp dimming, even after only a few hundred hours you will have only the same brightness as a brand new lamp in the first place, so you could just buy more new lamps for a lower cost for a single projector and have more brightness over time (unless you are willing to spend 2x as much on lamps, which is what you will have to do). I would just say that given the above, you will have a better image just buying a brighter projector or getting a very high gain screen. You also are going to increase your A/C costs if you are in a hot climate running 2 PJ's in a single room like that at the same time, as well as twice the electricity usage of two projectors (not much but it all ads up). The two lamps being at an uneven brightness will actually reduce your Native On/Off contrast anyways because you will have to compensate your IRIS settings and calibration due to mismatched brightness and colors.

Darker blacks are good, but at some point you mise well just forget it and be realistic about it. It just seems kind of fruitless for a lot of extra money, but whatever floats your boat. It actually makes a lot more sense for 3D than it does for 2D, at least with 3D you have a JVC level image that doesn't ghost as much by using 2 projectors.


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post #7 of 17 Old 08-08-2012, 04:43 AM
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Quote:
Originally Posted by coderguy View Post

My comments applied to 2D as well, again you are burning 2 lamps at the same time, you will have a softer image, and as the lamps age at different rates you will limit the usefulness due to increasing brightness unevenly on the overlap. Since the convergence won't be perfectly aligned, whichever projector ends up putting out the brighter image is going to stick out which will force you to lower the IRIS settings anyhow. It also doesn't make sense because due to lamp dimming, even after only a few hundred hours you will have only the same brightness as a brand new lamp in the first place, so you could just buy more new lamps for a lower cost for a single projector and have more brightness over time (unless you are willing to spend 2x as much on lamps, which is what you will have to do). I would just say that given the above, you will have a better image just buying a brighter projector or getting a very high gain screen. You also are going to increase your A/C costs if you are in a hot climate running 2 PJ's in a single room like that at the same time, as well as twice the electricity usage of two projectors (not much but it all ads up). The two lamps being at an uneven brightness will actually reduce your Native On/Off contrast anyways because you will have to compensate your IRIS settings and calibration due to mismatched brightness and colors.
Darker blacks are good, but at some point you mise well just forget it and be realistic about it. It just seems kind of fruitless for a lot of extra money, but whatever floats your boat. It actually makes a lot more sense for 3D than it does for 2D, at least with 3D you have a JVC level image that doesn't ghost as much by using 2 projectors.

I'm not saying I'd do it, but if you've need 1600+ lumens, you don't have a lot of choices. The best option is something like a Lumis, or HT5000, but those are hugely expensive, "buying a brighter projector" just isn't a realistic option always. Nor is getting a screen with high gain, if you want/need an AT screen you're near or below unity gain.

If we assume that it's practical to align two projectors (which I don't think it is) what else would give you >1500 Lumens and >20k:1 contrast? Two RS45s would do that, about the only other option is the Sim2 Lumis which is at least twice as expensive as two RS45s.

I'm just saying the idea makes a lot of sense, unfortunately it's just not practical to implement.

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post #8 of 17 Old 08-08-2012, 05:45 AM
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Or buy a new bulb after a couple of hundred hours biggrin.gif
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post #9 of 17 Old 08-08-2012, 08:02 AM
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You can buy a bulb after every movie for an RS45 and it will never do 1600 Lumens. Same is true for basically every projector under $20k, unless you get into business or pseudo-business units that have huge light output but questionable calibration and performance.

See what an anamorphoscopic lens can do, see movies the way they were meant to be seen
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post #10 of 17 Old 08-08-2012, 08:23 AM
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Quote:
Originally Posted by stanger89 View Post

With a CRT you can adjust the picture size/shape basically however you want, you can pull a corner in a bit, or push it out, so you've got a lot of degrees of freedom when it comes to lining up the two images.
When you get to a digital, there's only at most three degrees of freedom (often less). The main one is zoom, to adjust the size, the other is vertical shift, to shift it up and down, and then horizontal shift but that's somewhat rare. But these are all global adjustments. So if you get three corners/sides lined up with a digital and the fourth isn't, you're sorta stuck, or at best you have to remount it to fix it.
As I suspected; thanks for confirming in detail stanger89.
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post #11 of 17 Old 08-08-2012, 08:44 AM
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Originally Posted by stanger89 View Post

(which I don't think it is) what else would give you >1500 Lumens and >20k:1 contrast?

The Epson 5010 can do it out of best mode but still with color that should be close enough for most peoples' taste, although it is a bit rougher looking and of course only with the IRIS, but I'd put my bets on a well converged 5010 over two stacked RS-45's for overall viewing experience, even though a single RS-45 would beat it. You won't get 1600 lumens out of (2) RS-45's for very long. You can align 2 projectors even of different types, I've done it before while just playing around, but how well the convergence lines up will be partly luck and the amount of softness will depend on this luck (even with 2 of the same projector).


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post #12 of 17 Old 08-08-2012, 09:09 AM
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Quote:
Originally Posted by coderguy View Post

The Epson 5010 can do it out of best mode but still with color that should be close enough for most peoples' taste, although it is a bit rougher looking and of course only with the IRIS, but I'd put my bets on a well converged 5010 over two stacked RS-45's for overall viewing experience, even though a single RS-45 would beat it. You won't get 1600 lumens out of (2) RS-45's for very long. You can align 2 projectors even of different types, I've done it before while just playing around, but how well the convergence lines up will be partly luck and the amount of softness will depend on this luck (even with 2 of the same projector).

Kind of off topic, but which mode on the 5010 would you calibrate to get the most lumens and be close enough for most peoples taste....Id assume living room or dynamic right?
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post #13 of 17 Old 08-08-2012, 09:21 AM
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Dynamic mode will generally give you 1400 to 1800 lumens at closest throw even with the color tracking fairly close to 6500k to 7000k, not sure how accurate the gammut looks in this mode but it isn't that far off. The mode isn't perfect, but it's probably better than any other projector can do at this high lumens and still have good contrast.


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post #14 of 17 Old 08-12-2012, 07:20 PM - Thread Starter
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For size, assume something in the range of 13' to 15' wide scope AT with desire for 3D.

Obviously "buy a brighter projector" but what single projector is available to light that size screen without seriously compromising CR?

I am not aware of any so that's why I was looking into a double or quad stack of JVC.

 

 

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post #15 of 17 Old 08-12-2012, 08:45 PM
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The Epson 5010 in dynamic mode is just as brighter or brighter than 2 stacked JVC's, at closet throw anyhow and especially after some lamp wear.


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post #16 of 17 Old 08-13-2012, 10:06 AM
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Quote:
Originally Posted by coderguy View Post

JVC has enough brightness for a large screen if you get some gain (depending on how large we are talking). Actually the JVC is brighter than most DLP's in best mode, unless we are talking DLP's with much worse black levels.
Why do people not often do this?
Well there are a few that are doing it mainly for 3D, but I'm not convinced. My reasoning is because you can just get a brighter model projector or buy two DIFFERENT non-stacked projectors instead of stacking two of the same. With two different projectors you get different Pro's/Con's making for a more solid overall experience. For instance, the Epson 5010 and Benq w7000 both have a 1500 lumens mode and both do better in 3D than a JVC. Even if you do not care about 3D, there are 2D advantages to owning more than one model. As good as the JVC is in many movies in 2D on Blurays, there are still 2D weaknesses to its image depending on the content. I can find some movies I still would rather watch on a DLP (not that many though), but for poorer sources, TV, or some stuff, certain DLP's are just going to process things better than the JVC anyways. The JVC needs a well-filmed Bluray that was mastered correctly to look its best, but when you feed it that, it does look spectacular.
So owning two of the same model seems like a huge waste of money to get stuck with the same Pro's/Con's. So the gain in brightness you get from double stacking you can just buy a secondary projector that is brighter for when you need that extra brightness. With stacking, you have color matching accuracy issues, convergence matching, and brightness variations between the two units which will further degrade the image over time. You also are burning two lamps instead of one at a time. You mise well just put the "stacking" budgets to buying many extra lamps and use new lamps more often providing extra brightness.

Problem is you raise the already high black level. Blending is the better solution, eventhough you still have to raise the black-level to match the blend zone(s). Immersive Display has been using the mini-led projectors in demo's for the past few years.

For 3D, at some point you just can't get a bigger projector (right Wolfgang;-)), so you get two. This also allows for passive 3D, wich generally is easier on the eyes.
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post #17 of 17 Old 08-20-2012, 06:32 AM
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Quote:
Originally Posted by Laserfan View Post

I'm curious as to "why". Is it simply that CRT projection, being analog, has (in theory anyway) infinite adjustability vs. digital?

Definitely part of it. With CRT's you actually have to bring in all zones. But still they are "soft" for lack of a better term. With digital you have to attempt to line up all pixels exactly. That in and of itself is hard. Plus, being digital and generally razor sharp, you tend to lose that since getting them to align "perfectly" is near impossible.

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