Does anyone actually believe the nonsensical contrast ratios specs? - Page 4 - AVS Forum
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post #91 of 185 Old 02-20-2014, 11:35 AM
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Yeah, it was a lot more complicated, or maybe I should say a gray area in the early days of CRT. DLPs were the clear leader in overall contrast, but they had better On/Off and ANSI than the other technologies, which sort of obscured the reality. But these days with JVCs having enormous On/Off contrast and mediocre ANSI, but DLPs being the reverse, it's a lot more clear, and more data to back up those who really knew what was going on with CRTs had known for a long time.

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post #92 of 185 Old 02-20-2014, 02:02 PM
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Originally Posted by stanger89 View Post

I think Darin has gone into some depth about this before, but the short version is the more you close down the light path, especially at the lens, the less stray, "waste" light is allowed through, since you block more waste light than desired light, the contrast ratio goes up.

It's the same reason why you don't see really bright projectors with really good contrast, a light engine that produces high contrast eats a lot of light.
And if you stop down the lens on any DSLR contrast performance of the lens itself increases. And it's not optical trickery.... smile.gif

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post #93 of 185 Old 02-20-2014, 02:37 PM
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Originally Posted by Kris Deering View Post


I'm sure most of the Sim2, Titan, Barco, Christie and every other big DLP manufacturer owner over there would LOVE to get more on/off contrast on top of that brightness. Bright projectors do a great job of lighting up enormous screens but when it's time for a dark image in a home theater their achilles heel shows very quickly, despite large ANSI contrast numbers.

Have you now done a direct comparison between high end single chip DLP and JVC lcos?

 

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Originally Posted by Kris Deering View Post

Haven't done direct comparisons with the big pro style single chips. 
 

While JVC has far higher on/off contrast I am not so confident that a JVC would be the clear winner in image quality even in dark scenes.

 

I own a old PojectionDesign projector that claims 1,200:1 to 7,500:1 native contrast, 5,000 to under 1,000 Lumens. ANSI checker board contrast I assume is high considering the lens I believe originally cost about 2K and has no zoom element. 

 

I am using it in single lamp mode with the iris stepped down but not fully, and some vertical lens shift which appears to improve contrast, Film2 gamma about  2.5. 

 

It looks excellent in dark scenes like those in the SciFi Pandorum and Aliens vs Predator 2 and excellent  in bright scenes like in the film Sahara. I don't see this "Achilles heel" picture quality doesn't drop in dark scenes. 

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post #94 of 185 Old 02-20-2014, 02:48 PM
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Originally Posted by Mark77771 View Post

Have you now done a direct comparison between high end single chip DLP and JVC lcos?

While JVC has far higher on/off contrast I am not so confident that a JVC would be the clear winner in image quality even in dark scenes.

I own a old PojectionDesign projector that claims 1,200:1 to 7,500:1 native contrast, 5,000 to under 1,000 Lumens. ANSI I assume is high considering the lens I believe originally cost about 2K and has no zoom element. 

I am using it in single lamp mode with the iris stepped down but not fully, and some vertical lens shift which appears to improve contrast, Film2 gamma about  2.5. 

It looks excellent in dark scenes like those in the SciFi Pandorum and Aliens vs Predator 2 and excellent  in bright scenes like in the film Sahara. I don't see this "Achilles heel" picture quality doesn't drop in dark scenes. 

I haven't done a direct comparison with one of the bigger DLP projectors in my room (I mean 3-chip designs like DP or Sim2) but I've compared it directly to the higher contrast DLPs like those from Sharp, Marantz, Samsung and Planar. With low to mid APL scenes there is no competition here at all. I've heard so many people with high end DLPs say they think their blacks look great and then they do a direct comparison with something like the JVC and they see first hand how far away from real blacks they are getting. I am no way saying that these projectors don't throw a good image, they can look fantastic with most material and their ability to throw a bright image on huge screens with outstanding sharpness is a testiment to what you can do at home. But when you are talking on screen contrast and black levels, they aren't even in the same universe.

Also, I don't know how you can pull of a power gamma of 2.5 with that projector. You would be clipping well before black as the low end levels aren't nearly low enough for a linear gamma of that value. It would probably be a stretch for 2.35. There are calculators for this online. You'd be better off with BT.1886 or running a 2.2 - 2.3.

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post #95 of 185 Old 02-20-2014, 03:09 PM
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Originally Posted by Kris Deering View Post

Also, I don't know how you can pull of a power gamma of 2.5 with that projector. You would be clipping well before black as the low end levels aren't nearly low enough for a linear gamma of that value. It would probably be a stretch for 2.35. There are calculators for this online. You'd be better off with BT.1886 or running a 2.2 - 2.3.

Cine4home have a review of a similar projector to the one I own. Film2 on my projector also looks the best. According to test patterns my projector is not clipping black.

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In "Film 1" (chart above), the projector goes to the limits of its performance: with a particularly steep increase of 2.65 contrasts between light and dark are highlighted particularly strong, the image subjectively more spacious. The disadvantage of this setting: Many nuances are moved to a very dark area, so that in non-optimized rooms dark details are outshone quickly diffused light. Praiseworthy is the fact that even in this mode, the projector no details are swallowed (due to its dark segment in the color wheel), but an optimized space here is almost mandatory. This mode can be combined with, for example, not quite closed iris.

 

When using the Film2 presets the projector displays with an increase of approximately 2.5, a not quite as steep gamma. Here he offers in dark areas of an improved level, so that this mode is particularly recommended. In a darkened room with minimal light spill it leads to a good image depth, both in dark and bright scenes.

 

"Video1" mode, the projector is slightly below the video standard (2.2 ratio), which is currently used with with video mastering. This raises gamma preset dark details even more and is therefore universally applicable, but the picture does not show enough depth image.

http://www.cine4home.de/tests/projektoren/PDAction3/Action3Test.htm

They give some contrast measurements. Unfortunately they don't state if they experimented with vertical lens shift as on my projector some vertical lens shift appears to visibility improve contrast. They also don't state what lens option they were using, I have the EN15 which is fixed focal length so no zoom element.

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post #96 of 185 Old 02-20-2014, 03:33 PM
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Quote:
Originally Posted by Kris Deering View Post

I haven't done a direct comparison with one of the bigger DLP projectors in my room (I mean 3-chip designs like DP or Sim2) but I've compared it directly to the higher contrast DLPs like those from Sharp, Marantz, Samsung and Planar. With low to mid APL scenes there is no competition here at all. I've heard so many people with high end DLPs say they think their blacks look great and then they do a direct comparison with something like the JVC and they see first hand how far away from real blacks they are getting. I am no way saying that these projectors don't throw a good image, they can look fantastic with most material and their ability to throw a bright image on huge screens with outstanding sharpness is a testiment to what you can do at home. But when you are talking on screen contrast and black levels, they aren't even in the same universe.

Also, I don't know how you can pull of a power gamma of 2.5 with that projector. You would be clipping well before black as the low end levels aren't nearly low enough for a linear gamma of that value. It would probably be a stretch for 2.35. There are calculators for this online. You'd be better off with BT.1886 or running a 2.2 - 2.3.

I have done a side by side test with the Lumis 3DS and VW1000 and the biggest difference was in dark scenes so in very dark scenes where the new JVC´s is much better than the VW1000 the difference to the Lumis would be even bigger. The Sony had a better picture all over the scale than the Lumis, the only points the Lumis had the upper hand was in brightness and 3D and I think the Lumis would get relly hard competition compared to the new JVC´s as well.smile.gif

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post #97 of 185 Old 02-20-2014, 05:28 PM
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Quote:
Originally Posted by Mark77771 View Post

They also don't state what lens option they were using, I have the EN15 which is fixed focal length so no zoom element.
I'm guessing that is a really nice lens with high ANSI CR and high MTF at high resolutions. I still suspect the higher intra-image contrast ratios the JVCs can achieve in some dark material would be pretty clear if shown in the same room, even if they look good without that other reference to compare to, but that non-zoom lens with a single chip DLP is probably about as sharp as you can get from 1080p.

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post #98 of 185 Old 02-20-2014, 07:01 PM - Thread Starter
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I've read back through most of the posts but still have a couple things that I don't understand and still question the validity and credibility of published and reviewed specifications. Darin you appear to share my position to some degree.
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Even with manufacturers who have been pretty reliable some of us try to keep an eye on things. For instance, I would consider the extra dynamic on/off CR that JVC claims for the models above the 49 and 4910 to be pretty much marketing numbers and not based in reality. In reality I think the best dynamic on/off CRs of all 3 levels (49, 57, and 67) are likely pretty close.

Question/Commnets
1. My understanding of native contrast is the abilities of the projector with no help from any other contrast improving mechanisms specifically something like an iris. Dynamic on the other hand can use whatever magic possible.
Tom Huffman also believes this to be the case. BTW he also shares my skepticism of published contrast ratios. But I digress. Please read his article here. http://www.chromapure.com/colorscience-contrast.asp

Also given that no two manufactures or models implement the same type of iris. Some don't even have an iris. Some can't be defeated.

So I ask again why is this an acceptable procedure when trying to determine native contrast?

2. If setting the iris to its fully closed position does not artificially inflate CR why does the contrast drop when the iris is opened? If the iris was left open or closed throughout the entire testing procedure with the notion that the iris does not effect contrast ratio the ratios would be the same as the white points would be inversely effected.

3. With a meter like the Minolta what is the highest level of contrast that can be measured? I have ordered one BTW to replace my ancient Canon.

Thanks in advance for your wisdom.
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post #99 of 185 Old 02-20-2014, 10:33 PM
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Originally Posted by trans_lux View Post

So I ask again why is this an acceptable procedure when trying to determine native contrast?
One reason is to look at why we care about the differences between the two main types of on/off CR that we dicuss here. We just needed names that would let people know which one we were talking about. Much of this is simplified for illustration purposes, but hopefully it will help.

The first type is where no matter what the image content is the projector can display white pixels just as bright for each one as if it is displaying a full screen of white. So, if white is say 12 ft-lamberts, whatever white that takes for each pixel to achieve that, if there is a scene with bright white headlights that are small on a pretty much black background, the projector can still project those white pixels as the same level as it can it bright images.

If a projector can maintain that white it is pretty much doing the best kind of on/off CR. That is, the white point isn't being moved around based on image content. The projector lens openings (lens iris basically) and other openings inside (like a lamp iris) are basically fixed and whatever the projector can achieve for white in bright scenes it can achieve in dim scenes. Some of use ended up calling that native on/off CR. This was to differentiate from another kind of on/off CR.

That is one where the projector decides on the fly where the best iris position, lamp output, or LED output will be. As images dim the amount of light that white pixels can put out the lens goes down. If a scene is all dark pixels then this tends to work well. For instance, if the brightest pixel in an image were 50% video level the light that would call for is about 20% of white and the projector could move its white range down about 5x and then multiply the light for every pixel at the panels by 5 except for black pixels and put out the full value for the 50% video level pixels while lowering black maybe 5x (or maybe more if the iris increases the native on/off that is relevant to that scene).

This dynamic moving is not easy to do because our eyes can actually pick up on certain things. Some of us have decided that with projectors with maybe 10k:1 native on/off CR or less a multiplier beyond around 3x-4x to dynamic on/off CR would cause more harm than good. It depends on how good the dynamic implementation is, but in general I think that there has been some truth to that. I think JVC is able to have a bigger multiplier because they start with a higher native on/off CR.

Not sure if that made sense, but another way to look at it is that no matter what we call it, the total range that a display can do at one setting without moving the white point dynamically is important. If I have an iris set to position -10 then that range that it could do while at -0 (more open) is pretty much irrelevant to the performance I am getting now. I chose a more closed iris position and get to benefit from the more efficient optical path, so there is no reason to report the performance at -10 as less than I can get at -10. The manufacturer could have shipped the projector with the irises fixed in those positions if they had wanted to. We benefit from them giving us choices, but a projector where the user picks a closed down iris position is not performing worse than one where the manufacturer chose a fixed close down iris position (all else being equal) and it shouldn't be graded as if it is.

We wouldn't say that we have to report the lumens as what they were for the irises being closed if the user can just always use the projector with them open. It is a little dubious to report the lumens in one iris setting and the contrast ratio with a different iris setting, but at least it is something many people around here have known about for a while and we just take that into account when looking at the performances for those projectors.
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Originally Posted by trans_lux View Post

2. If setting the iris to its fully closed position does not artificially inflate CR why does the contrast drop when the iris is opened?
It is due to some physics that may not be that easy to explain. I'm going to try something and hopefully it will work. The closing of the irises helps the real native on/off CR as long as they are implemented correctly.

Try picturing the cross section of a projector lens about halfway down the barrel, where an iris might go. Now take every lens element off the front of the lens there. Then imagine taking a piece of paper, cut it to about the inside diameter of the lens, lay a dime on the center of it and draw a circle around that, then lay a quarter on it and draw a circle around that (so just outside the dime's circle). Now put this piece of paper in the lens where an iris might go.

Now feed the projector a full black image and imagine that what you see on the paper is just a uniform dark gray. It isn't any brighter in the center than out at the edges. Now feed the projector a full white image and image that what you see is that in the area of the dime's circle there is super bright white, in the area just outside that but inside the quarter's circle is light that is about half as bright. Then outside the quarter's circle is a little lower level of gray.

For this example let's image that the contrast ratio of that light inside the dime is 40k:1, the contrast ratio for the light in the next ring is about 20k:1, and the light outside the quarter's circle has a contrast ratio of about 10k:1.

Now you get to decide how big an iris to put in there. Let's say that if you make the opening the size of a dime and put it in the exact right spot your projector will output 500 lumens with 40k:1 on/off CR. If you decide to make the opening the size of the quarter I'll assume twice the area (so twice the black level), but only 50% more light (since the light in that ring is half as bright). So, you can now get 750 lumens, but now the on/off CR is only 30k:1 (an even mixture of 40k:1 and 20k:1).

If you really need more than 750 lumens then maybe you just let the lens be totally open so you can get maybe 900 to 1000 lumens, but then you pull the overall on/off CR down even more as you open up some areas that are only 10k:1.

Summarizing for this example I just totally made up the manufacturer could choose between these, with iris size:

Dime: 500 lumens and 40k:1 on/off CR
Quarter: 750 lumens and 30k:1 on/off CR
No iris: 900-1000 lumens and 20k:1 on/off CR

As crazy as it might sound to take the front part off a lens and put a piece of paper in there to see where the light is travelling through the lens for full screen white and black images, I have done just that. I modified an Optoma H79 to about 9k:1 on/off CR at maybe 100 lumens or so (for use with a high gain screen) back when the best on/off CR I could buy in digitals was probably around 4k:1. That was using 2 irises though and in other posts I've gone into some of the reasons that an iris by the lamp combined with an iris in lens works very well for DLPs.
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Originally Posted by trans_lux View Post

3. With a meter like the Minolta what is the highest level of contrast that can be measured?
There are a lot of variables, so I'm just going to throw out a gut feeling. For on/off CR with the T10 I think around 500k:1 with plus or minus 100k:1 is probably pretty reasonable to be able to do without doing anything crazy. Just measuring near the lens. If you want lots more accuracy then that goes down some.

For ANSI CR a lot depends on the room and making sure there aren't unwanted reflections getting into the black level readings.

I know it is possible that my explanations above didn't make any sense. If that is the case somebody can let me know. smile.gif

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post #100 of 185 Old 02-20-2014, 11:18 PM
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Also when measuring cr you can utilize different tricks to increase the range of the measurement. For example measuring with a pattern with only 0 and 5% white as darin suggested or measuring the black and white points at different distances from the lens. You can then calculate the light drop introduced by increasing the distance when doing the white point and adjust the ratio accordingly to get an accurate cr measurement. An nd filter would also work.
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post #101 of 185 Old 02-21-2014, 01:30 AM
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Quote:
Originally Posted by trans_lux View Post

Question/Commnets
1. My understanding of native contrast is the abilities of the projector with no help from any other contrast improving mechanisms specifically something like an iris. Dynamic on the other hand can use whatever magic possible.

So I ask again why is this an acceptable procedure when trying to determine native contrast?

As far as I am aware unless the manufacturer states differently.

Native contrast is the maximum on/off contrast sequential contrast with dynamic iris and dynamic black turned off the projector is capable of. Using any iris at fully closed down (likely to be too low lumen output for most uses) the native color of the projector (not calibrated for use, not accurate color) and using any other tricks to enhance contrast regardless of the effect on image accuracy, for single chip dlp things like brilliant color secondary color wheel segments, white peaking using a white segment or spoke time.

 

As it is not unless otherwise stated native contrast at a stated lumen output with an accurate picture it is usually marketing spiel.

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post #102 of 185 Old 02-21-2014, 05:03 AM
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Quote:
Originally Posted by trans_lux View Post

I've read back through most of the posts but still have a couple things that I don't understand and still question the validity and credibility of published and reviewed specifications. Darin you appear to share my position to some degree.

Strictly speaking about the manufacturer provided numbers, I think we all agree that at best, you look at them with a "trust but verify" mindset, often times you can just completely ignore them as being worthless. Which one you look at depends on the manufacturer's track record for "exageration".

On the other hand, the measurements provided by independent third parties, I think most here would agree that they are very valuable and useful, even if not 100% comparable from measurer to measurer, though they often do corroborate each other.
Quote:
Question/Commnets
1. My understanding of native contrast is the abilities of the projector with no help from any other contrast improving mechanisms specifically something like an iris. Dynamic on the other hand can use whatever magic possible.
Tom Huffman also believes this to be the case. BTW he also shares my skepticism of published contrast ratios. But I digress. Please read his article here. http://www.chromapure.com/colorscience-contrast.asp

I would amend this to say no dynamic contrast improving mechanisms. And yes, most agree that you shouldn't just believe manufacturer specs, it's always best to look at independent measurements (ie Cine4Home, Kraine, Zombie, Kris, etc...)
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Also given that no two manufactures or models implement the same type of iris. Some don't even have an iris. Some can't be defeated.

This is IMO irrelevant, it's no different than low vs high lamp mode or one vs two lamps. If you have an iris (static, manually adjustable), "native" contrast is no different than ANSI lumens if you have multiple lamp modes or multiple lamps. For example your projector has 2 lamps correct? What's the native brightness of your projector? There's probably 4 different brightnesses one could measure, 1 lamp eco, 1 lamp high, 2 lamp eco, 2 lamp high. On and if you've got a adjustable iris, that multiplies the number of brightnesses one could measure as well.
Quote:
So I ask again why is this an acceptable procedure when trying to determine native contrast?

In a nutshell:
  1. Disable all dynamic contrast/brightness adjusting features
  2. Display full white field - Measure brightness
  3. Display full black field - Measure brightness
  4. Divide white measurement by black measurement to determine "native" contrast
  5. Do the above for the highest contrast configuration, and ideally repeat for each, or at least a representative sample of configurations

Ideally everyone would publish a table of "native" contrast measurements like Cine4Home does for JVCs, for multiple lamp modes, throw distances, iris settings. Cine4Home really provides the "best" (ie most complete) measurements I've seen.

But to really understand the contrast performance of a display, you'd need to do what Mark P did in the Contrast Thread, and that's quite the undertaking.
Quote:
2. If setting the iris to its fully closed position does not artificially inflate CR why does the contrast drop when the iris is opened? If the iris was left open or closed throughout the entire testing procedure with the notion that the iris does not effect contrast ratio the ratios would be the same as the white points would be inversely effected.

Darin provided a great explanation, but let me try a more "theoretical" one. Basically the ideal projector would pass all light that's meant to hit the screen and block all light that is not meant to, in this ideal projector the contrast ratio would be infinite, black would be zero, and all light would be well focused onto the screen. Reality is of course that light that is not meant to hit the screen does, this is waste light. It is not well focused, and it is, effectively of constant intensity. On the other hand the light that is meant to hit the screen is quite well focused through the light path.

If you put a fixed or manually adjustable (but otherwise static) iris in the light path, you can block both of these types of light, but as you close down the light path, you block a higher percentage of the waste light than you do the "desired" light, this increases the contrast ratio because you've reduced the level of black by more than the level of white. This is, I believe, exactly what CINERAMAX does with his SuperKontrast DCI machines. Since in the home you don't need the enormous light output, he puts more restrictive irises in thus reducing the efficiency of the light path, but increasing the contrast.
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Originally Posted by darinp2 View Post

As crazy as it might sound to take the front part off a lens and put a piece of paper in there to see where the light is travelling through the lens for full screen white and black images, I have done just that. I modified an Optoma H79 to about 9k:1 on/off CR at maybe 100 lumens or so (for use with a high gain screen) back when the best on/off CR I could buy in digitals was probably around 4k:1. That was using 2 irises though and in other posts I've gone into some of the reasons that an iris by the lamp combined with an iris in lens works very well for DLPs.

Didn't you post pictures of that? I remember seeing pictures of some projector taken apart with a piece of paper shoved in before the lens, and you could clearly see two shapes with two different levels of light coming out when "white" was projected.

See what an anamorphoscopic lens can do, see movies the way they were meant to be seen
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post #103 of 185 Old 02-21-2014, 08:00 AM
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I may have posted pictures, but I don't remember. I did find a thread were I described what I did and some about how the same on/off CR that is strong in red down low is better than one weak in red given how our eyes are not very sensitive to very low light levels of red:

http://www.avsforum.com/t/678034/getting-about-9k-1-on-off-cr-from-an-h79

We could take measurements to another level and apply the human sensitivity to different wavelengths in very dark images for the absolute black level, but not sure how hard that would be.

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post #104 of 185 Old 02-21-2014, 02:47 PM
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Quote:
Originally Posted by Andreas21 View Post

To me the combination of high on/off and high ANSI will give you the projector with the most dynamic over all picture. If you only have high on/off and very low ANSI like a CRT ith throws a very boring picture to me, but of corse very good black levels. If you have a projector with very high ANSI and low on/off like many DLP´s iit can show very dynamic bright pictures, but it looks very poor in low APL scenes. And if you take projectors with quite high numbers on both like the latest JVC´s and Sonys they throw a very good and dynamic picture in the whole range of scenes in a movie. Comparing the new JVC´s to the new 4K Sonys it is quite easy to see the higher on/off of the JVC gives it an advantage ing very low APL scenes and the higher ANSI of the Sonys gives it an advantage in scenes with more light even if they are brightness matched. I have no sience to back this up, but I have seen this when I have side by side tested this years JVC (X500) against the VW500 and VW1000. The new ILA feature of the new JVC´s is a clear upgrade from last years models, but only in the very low APL scenes.

And I have a question here regarding on/off contrast. Since the X500 has a native contrast of 60000:1 and the X700 has 120000:1 will the difference between them be easy to see??wink.gif


smile.gif

Ofcourse, it will be. at least, twice as easy to see and twice as good biggrin.gifwink.gif


dj
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post #105 of 185 Old 02-21-2014, 03:22 PM
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Quote:
Originally Posted by trans_lux View Post

You couldn't be more wrong.
Despite my distrust of the specified contrast numbers I think the current generation of Sony projectors especially the 55ES & 1000/1100ES are fantastic projectors.
I also like the X900R on the right screen size and environment I think it looks great. I even like e-shift.
I have all on the way for further evaluation.
With the plan to be to purchase a 1100ES for myself.



Dont do that, it has a ( relatively ) high on/off Cr eek.gif ! biggrin.gif

But also a ( realtively ) high ANSI / intrascene CR, so maybe you could live with it, after all smile.gif

dj


BTW.

measurred "real" Native CR on/off ( iris off ) arround 10K - 15K and "dynamic" CR on/off ( iris full ) 150K - 500K , the "ansi CR" about 500 - 800 ( if you have the correct - all Black - room ) I think.
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post #106 of 185 Old 02-21-2014, 03:56 PM - Thread Starter
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Quote:
Originally Posted by d.j. View Post

Quote:
Originally Posted by trans_lux View Post

You couldn't be more wrong.
Despite my distrust of the specified contrast numbers I think the current generation of Sony projectors especially the 55ES & 1000/1100ES are fantastic projectors.
I also like the X900R on the right screen size and environment I think it looks great. I even like e-shift.
I have all on the way for further evaluation.
With the plan to be to purchase a 1100ES for myself.



Dont do that, it has a ( relatively ) high on/off Cr eek.gif ! biggrin.gif

But also a ( realtively ) high ANSI / intrascene CR, so maybe you could live with it, after all smile.gif

dj


BTW.

measurred "real" Native CR on/off ( iris off ) arround 10K - 15K and "dynamic" CR on/off ( iris full ) 150K - 500K , the "ansi CR" about 500 - 800 ( if you have the correct - all Black - room ) I think.

For the Sony 1100?
Yes the 1,000,000:1 CR is only possible on the dark side of the moon wink.gif
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post #107 of 185 Old 02-21-2014, 04:39 PM
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Quote:
Originally Posted by trans_lux View Post

For the Sony 1100?
Yes the 1,000,000:1 CR is only possible on the dark side of the moon wink.gif



nahh, I think Cine4home meassurred about 900.000:1 ( see : http://cine4home.de/knowhow/Cine4Home_Edition_Sony_VW1000/Sony_VPL_VW1000-C4HEd.htm )

"Der hohe dynamische Kontrast wird durch eine aggressivere Programmierung der Iris im Brennpunkt des Objektives erreicht (Modus „Iris Auto Voll“): Sie schließt nun deutlich stärker, als bei den Vorgängern VW90/VW95. Damit wird in der Serie tatsächlich ein messtechnischer Wert von ca. 900,000:1 erreicht (native Farbtemperatur, kleinster Zoom)."


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post #108 of 185 Old 02-21-2014, 04:56 PM
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Quote:
Originally Posted by d.j. View Post

nahh, I think Cine4home meassurred about 900.000:1 ( see : http://cine4home.de/knowhow/Cine4Home_Edition_Sony_VW1000/Sony_VPL_VW1000-C4HEd.htm )

"Der hohe dynamische Kontrast wird durch eine aggressivere Programmierung der Iris im Brennpunkt des Objektives erreicht (Modus „Iris Auto Voll“): Sie schließt nun deutlich stärker, als bei den Vorgängern VW90/VW95. Damit wird in der Serie tatsächlich ein messtechnischer Wert von ca. 900,000:1 erreicht (native Farbtemperatur, kleinster Zoom)."


dj

Translated into english:
Quote:
The high dynamic contrast is a more aggressive programming of the iris in the focal point of the objective achieved (mode "Auto Iris Full"): it now includes significantly more powerful than its predecessors VW90/VW95. In order for a metrological value is actually in the range of approximately 900,000:1 reached (native color temperature, smallest zoom).

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post #109 of 185 Old 02-22-2014, 02:24 PM - Thread Starter
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So what does one use to measure 900,000:1? I know of nothing with those capabilities.
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post #110 of 185 Old 02-22-2014, 02:52 PM
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Quote:
Originally Posted by trans_lux View Post

So what does one use to measure 900,000:1? I know of nothing with those capabilities.

There are more sensitive meters than the T10.

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post #111 of 185 Old 02-22-2014, 09:55 PM
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Also remember that if you are measuring right near the lens the black floor isn't nearly as low as it is on screen. With a bright projector like the Sony a lot of that number is up high.

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post #112 of 185 Old 02-23-2014, 12:35 AM
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If your screen is normally 16' from the projector and you measure the white level from that distance and then move closer and measure the black level from 0.5' the black level will get amplified 1024 times compared to the white level. Now you can measure 1 million:1 contrast with a meter that is limited to 1.000:1.
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post #113 of 185 Old 02-24-2014, 04:44 AM
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Quote:
Originally Posted by trans_lux View Post

So what does one use to measure 900,000:1? I know of nothing with those capabilities.
I intended to remain silent, but I believe you've already asked that same question which was already addressed by Darin on the previous page...
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Originally Posted by darinp2 View Post

First I'll start with something related.

If I people were hired and asked to measure the length of a house with reasonable accuracy and were only given a 12' tape measure some of them would throw up their hands and say it wasn't possible, while others would just figure out a way to do it by doing multiple measurements and some math.
...
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post #114 of 185 Old 02-24-2014, 06:46 AM - Thread Starter
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The longer this post has gone on I feel more and more that my original statement and position has been validated.
On/off contrast is potentially important but there are so many variables and methods for obtaining measurements the numbers can't be used as any means of subjective evaluation of performance.
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post #115 of 185 Old 02-24-2014, 07:27 AM
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Originally Posted by trans_lux View Post

The longer this post has gone on I feel more and more that my original statement and position has been validated ....

Only in your own mind.
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post #116 of 185 Old 02-24-2014, 08:02 AM
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On a more meaningful note

The important thing to understand as clearly demonstrated is that native (Static on/off) is clearly only a part of the story as it is an optimistic view in a number of aspects

1) It doesn't take into account the APL of the current scene. As the scene increases APL the contrast reduces. For a JVC this means it could be anywhere near its rated on/off spec of say 60,000:1 (X500) to about 250:1 (ANSI)
2) The rated contrast is always optimistic meaning it only specifies
a) Longest throw
b) Aperture manual fully closed
c) Maximum output picture mode that is normally nowhere near D65 (e.g. SuperBright)
Perversely the rated ANSI lumen output is rated at shortest throw, aperture fully open also in SuperBright mode. This means it is never possible to have both max lumens and max contrast with the same projector positioning.
3) As the bulb ages, the more light loss is required to calibrate it to D65 as UHP bulbs diminish in red more quickly than other colours, requiring a cut of blue/green to compensate. Although the latest JVCs are much better in terms of bulb degradation, historically this meant you got futher and further away from rated specifications as the bulb aged. On top of this as the bulb output reduced you needed to open the aperture more worsening the contrast further.

Unfortunately although there is a standard (e.g ANSI) for measuring aspects like contrast and lumens, they are not meaningful in a typical use case scenario. The reality is that we are more often far away from the rated specifications that many realise. Dynamic contrast measurements confuse this even further. I do question the way things currently are, and would much prefer electronic companies forced to quote mid throw, mid aperture, no dynamic, at D65, with a 10-15% APL test scene, with the contrast AND brightness output for this scenario together. Then you have something meaningful, tangible and realistic to work with.
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post #117 of 185 Old 02-24-2014, 09:02 AM
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Quote:
Originally Posted by trans_lux View Post

The longer this post has gone on I feel more and more that my original statement and position has been validated.
On/off contrast is potentially important but there are so many variables and methods for obtaining measurements the numbers can't be used as any means of subjective evaluation of performance.

I'm not really sure where you're getting this. Yes the manufacturers specs should be looked at with appropriate skepticism, but the measurements from 3rd party reviewers are quite useful and usually consistent.

The numbers Cine4Home (for example) publishes for their reviews relate quite well to subjective impressions from many reviewers.

That and there really aren't "so many... methods", as near as I can tell pretty much everyone who measures on/off (independent reviewers) does it essentially the same way. Measure white, measure black, divide, and say whether you had the DI on or off.

It's just not that hard.

See what an anamorphoscopic lens can do, see movies the way they were meant to be seen
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post #118 of 185 Old 02-24-2014, 09:30 AM
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Quote:
Originally Posted by trans_lux View Post

The longer this post has gone on I feel more and more that my original statement and position has been validated.
On/off contrast is potentially important but there are so many variables and methods for obtaining measurements the numbers can't be used as any means of subjective evaluation of performance.
I'm going to quote where you made clear what your original position was so people can see that. Hopefully nobody will take this as being true, since it is pretty much nonsense:
Quote:
Originally Posted by trans_lux View Post

So can we agree that the full on/off method is a complete farce?
It's like saying I have 300 mph tires wink.gif
Given that our eyes only have the ability to see 100:1 in most situations to 10000:1 under absolutely ideal conditions and that as contrast increases our ability to discern differences diminishes very quickly what's the point?
I have measured real world contrast ratios of projectors that have rated on/off in the 100,000s and routinely see low 100s.
ANSI contrast should be the only benchmark that actually has anything to do with the real world.
I wonder if you honestly think you were right.

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post #119 of 185 Old 02-24-2014, 09:46 AM
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Yeah, that was pretty much on "reality-challenged" assertion after another in trans_lux's original post.
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post #120 of 185 Old 02-24-2014, 10:01 AM
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I think it comes down to: I have no idea what anyone is talking about here therefore it must be untrue. Simple as that, with PLENTY of proof throughout the thread to reinforce it. I think the mods should just close it down otherwise we just get into the feed the troll routine over and over again. You can lead a horse to water..............

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