How can projects provide insane static 30000:1 contrast ratio? - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 9 Old 11-02-2015, 10:21 AM - Thread Starter
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How can projects provide insane static 30000:1 contrast ratio?

I saw reviews of some very high-end and very expensive projectors supposedly having very high static contrast ratio of 30000:1 ! How is that possible? There is no way for projectors to produce plasma-level black levels no matter what background is used. The only way I see it possible is if these projects could provide VERY high brightness. Is that so? If not, then how do they provide such high contrast ratio?

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post #2 of 9 Old 11-02-2015, 10:53 AM
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No, they don't need much brightness, they need the ability to block the lamps light during dark scenes, but you need a fully darkened room to get that contrast, screen doesn't matter. The better they block it the better the on/off contrast. Even e very dim projector is able to achieve a very high contrast rating if his blacklevel is good enough.

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post #3 of 9 Old 11-02-2015, 11:18 AM
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^^^That.
Also, so far the only (non-CRT) models that can truly hit 30,000:1 contrast are specific JVC LCoS models, dual inline DMD DLPs (so far only available for commercial installation) and a direct laser-scanning projector that functions very much like the old CRT projectors (and is currently sporting some significant flaws in the present iteration).

So two of these are years from being completely viable public options while the JVC starts around $3000-3500.

All three are able to not only match, but exceed the contrast of most non-modified plasma televisions by a decent degree.

Everything else I've seen measured falls at least 3X short by comparison.

Easy $25 DIY black (or any color) ALR paint +$40-$50sprayer screen mix smooth/clean and very easy to learn spraying with little/no mess.
Simple $25-40 DIY black/dark-grey ambient-light rejecting screen, grab two things from a local store..mix..roll..done.
Quick <$250 dedicated black-fabric theater room "A store that sells blinds can help your picture more than a store that sells projectors many times." -bud16415
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post #4 of 9 Old 11-02-2015, 11:31 AM
 
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Quote:
Originally Posted by Ftoast View Post
^^^That.


Everything else I've seen measured falls at least 3X short by comparison.

Except for the LG PF-1500.

Last edited by Swolephile; 11-02-2015 at 12:02 PM.
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post #5 of 9 Old 11-02-2015, 01:07 PM
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Quote:
Originally Posted by Masharak View Post
I saw reviews of some very high-end and very expensive projectors supposedly having very high static contrast ratio of 30000:1 ! How is that possible? There is no way for projectors to produce plasma-level black levels no matter what background is used. The only way I see it possible is if these projects could provide VERY high brightness. Is that so? If not, then how do they provide such high contrast ratio?
It is amazing what they have done IMO, but we need to keep in mind that this is not ANSI CR, which uses a relatively extremely bright image at 50% luminance. This is more like a single white pixel on black. Still amazing to me that JVC can block up over 99.99% of the light for many of the pixels in such a pattern.

ANSI CR with lenses will probably never get that high and fortunately doesn't need to because our eyes don't need that much CR for such a bright image. Our eyes themselves have washout from bright objects to dark areas, but that isn't as limited with very small bright pixels on black.

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post #6 of 9 Old 11-02-2015, 01:11 PM - Thread Starter
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What is the usual cd/m^2 brightness for such high-end projectors? Any idea which projectors IMAX uses? When I watch films in IMAX theaters, I find black levels to be slightly better than those of good VA panels without local / micro dimming, but nowhere as good as plasma-level black levels.

I don't quite understand the whole light-blocking. I figured if a scene uses pure black somewhere, then the project would simply not use any light for that section in that scene. I also find plasma black levels to be much deeper than natural black levels of a very dark room (like the one in common or IMAX theater) to be nowhere as good as those of a plasma display. So, no matter how well a project can block light, black levels can't be that good, UNLESS brightness goes over 200 cd/m^2 or something like that.

Probes: i1Pro 2 & i1D3
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HDTV: Samsung LN40B550 40" CCFL SPVA LCD @ 1080p, 60Hz, 2700:1 CR; Monitor: LG 32GK850G-B 31.5" LED MVA LCD @ 1440p, 165Hz w/ G-Sync, 2500:1 CR
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post #7 of 9 Old 11-02-2015, 02:48 PM
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Most IMAX use a pair of 2000:1 contrast DLPs nowadays unless they are still rocking the film projectors which I believe measure higher though I sadly don't know how much.

A good VA can measure around 3000:1-4000:1 while a good plasma can hit 8000:1+ and a cheaper LCD will limit around 1000:1-1500:1.

A majority of commercial theaters measure 1800:1-2200:1.

A high-end LCD Epson 5025/5030 or LCoS Sony hits 4500:1-6000:1 while a JVC LCoS can reach well beyond 10,000:1+ as can AMOLED.


The noticeably poorer blacks you're seeing at IMAX rooms is due to safety regulations. A well-thoughtout hometheater can reach much deeper blacks by lacking sconces and EXIT signs and walkway lights and even using particularly dark fabric on surfaces closer to the screen in some cases.

My own "theater" room is blindingly dark when lights go down, and I did it for cheap and in a very easily reversed way.

Easy $25 DIY black (or any color) ALR paint +$40-$50sprayer screen mix smooth/clean and very easy to learn spraying with little/no mess.
Simple $25-40 DIY black/dark-grey ambient-light rejecting screen, grab two things from a local store..mix..roll..done.
Quick <$250 dedicated black-fabric theater room "A store that sells blinds can help your picture more than a store that sells projectors many times." -bud16415

Last edited by Ftoast; 11-02-2015 at 02:53 PM.
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post #8 of 9 Old 11-19-2015, 04:35 PM
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Quote:
Originally Posted by Masharak View Post
I don't quite understand the whole light-blocking. I figured if a scene uses pure black somewhere, then the project would simply not use any light for that section in that scene.
The projector has only a single light source, so the only way to "not use any light for that section" is to block it.
Quote:
So, no matter how well a project can block light, black levels can't be that good, UNLESS brightness goes over 200 cd/m^2 or something like that.
A bright home theatre projector is about 15 ftL, or 50 cd/m^2.
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post #9 of 9 Old 11-19-2015, 04:58 PM
 
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Quote:
Originally Posted by Ftoast View Post

A good VA can measure around 3000:1-4000:1 while a good plasma can hit 8000:1+ and a cheaper LCD will limit around 1000:1-1500:1.

A high-end LCD Epson 5025/5030 or LCoS Sony hits 4500:1-6000:1
I own and use all of the above and these numbers are dead on.
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