Asus Rog Swift PG278Q

[BrightCandle]

Just bare in mind what 'quality' means in this case is you prefer a monitor that has more accurate colour on static images over one with more accurate colours in motion. This screen will produce a closer to intended image when moving than an IPS screen does. I tend to play games that move which is why I favour these types of monitors. Of course with the static image quality on this screen being better than many IPS screens its really only the off axis colour shift that is an issue. I don't tend to move about such that it's an issue.

 

[Grooveriding]

Better colour in motion ? That is a logical fallacy. The monitor produces the colours it produces and it will produce visual distortion of those colours depending on its viewing angle characteristics. There is no 'better colour in motion' You may be mixing up the blur your eyes perceive with the actual colour reproduction the monitor delivers. It's important to understand just the vast difference between sitting in front of a TN and IPS. The latter has a uniform and consistent image while the former is inconsistent and will shift and distort with a general 'washed out' appearance depending on where you are and what portion of the screen your are looking at.

Are there any IPS screens this monitor delivers better colours than as you are inferring ? Which models in particular are you referring to ? You say 'many'. I'm not aware of even one IPS screen where with both being calibrated a TN will deliver better PQ. Which IPS model(s) in particular are you aware of that this TN screen has better colour reproduction than ?

Take the monitor on what it excels at; refresh rate and response times with the addition of gsync, rather than trying to pretend it's something it's not.

 

[bystander36]

IPS panels never reach the color that was intended if there is motion (at least at 120hz). They are always in flux the whole time a refresh takes place, so no, IPS panels are not going to have accurate color in motion. This same effect that causes the color to never reach it destination, or spend extremely little time at it's destination color is also why there is motion blur and ghosting.

 

[Mand]

Better colour in motion ? That is a logical fallacy. The monitor produces the colours it produces and it will produce visual distortion of those colours depending on its viewing angle characteristics. There is no 'better colour in motion' You may be mixing up the blur your eyes perceive with the actual colour reproduction the monitor delivers.

No, there is better color in motion and worse color in motion. A bad temporal response in the pixel can lead to the pixel not have completed its transition and sufficient dwell time at the desired color before it's commanded to switch to a new color, which results in temporal blending at the pixel level.

It is absolutely a thing, and it is something completely overlooked by the "IPS has better color under all conditions always" crowd. To think that a few levels' worth of color error at the extreme edge of the display is somehow utterly intolerable when every single pixel on the display is getting blurred together by anything other than a static image is something that somehow isn't a concern...

 

[hans030390]

I love the picture quality of my IPS display, but even overclocked to 120Hz, it's still a blur fest compared to a basic 120Hz TN panel. Lightboost is on a completely different level even still, though it's hard to get all games running at 100FPS or greater. I was hoping the IPS panel would be a good compromise, and it is, but the blur is starting to bother me more and more. I'm very sensitive to smooth and clear motion (literally gives me headaches otherwise). With G-Sync, seems like this Asus monitor will be fantastic for gaming. But I do hope the top/bottom of the screen look OK given its size.

 

[omeds]

Yeh oc'd IPS displays tend to look 'muddy' and blurry in motion, compared to 'quality' TN 120/144hz displays. What you're generally viewing on an oc'd IPS display is pixel transitions, not the completed image - or at least very little of it.

 

[bunnyfubbles]

Well the summation of this is basically; 'I prefer faster response times and higher refresh rates with less perceived blur over the quality of IPS'
I don't even notice blur in FPS games on my current monitor, so that is really moot to me.

I feel the opposite and would take better quality screens before any of those with the addition of those missing qualities as they become available on quality screens. Such as we see with the 120hz IPS from Overlord.

if you don't have experience with a low motion blur monitor (or its simply been too long since you've used CRT) then you cannot say you don't notice the blur because that's all you've ever seen since working with LCD, you simply don't know anything else and therefor it looks "fine" to you.

And, again, better quality is subjective, because the motion quality of a screen without LMB tech is going to be substantially worse.

An excellent tool to test just how horrible your screen is would be PixPerAn: http://www.prad.de/en/monitore/testsoftware/pixperan.html

120Hz without LMB tops out around level 8 on the readability test, with LMB the score can be maxed at 30, although most will run into limits of human potential/patience to score that high.

120Hz alone is good, definitely worthwhile over 60Hz, but I don't like to settle for lesser quality after experience LMB.

for gaming I will take motion clarity over static image quality any day, unless the game is Poison Berry Picking Simulator 2014, but considering the Rog Swift's TN panel is actually supposed to have good static image quality despite it being TN, well its win-win for me.

 

[Grooveriding]

if you don't have experience with a low motion blur monitor (or its simply been too long since you've used CRT) then you cannot say you don't notice the blur because that's all you've ever seen since working with LCD, you simply don't know anything else and therefor it looks "fine" to you.

And, again, better quality is subjective, because the motion quality of a screen without LMB tech is going to be substantially worse.

An excellent tool to test just how horrible your screen is would be PixPerAn: http://www.prad.de/en/monitore/testsoftware/pixperan.html

120Hz without LMB tops out around level 8 on the readability test, with LMB the score can be maxed at 30, although most will run into limits of human potential/patience to score that high.

120Hz alone is good, definitely worthwhile over 60Hz, but I don't like to settle for lesser quality after experience LMB.

for gaming I will take motion clarity over static image quality any day, unless the game is Poison Berry Picking Simulator 2014, but considering the Rog Swift's TN panel is actually supposed to have good static image quality despite it being TN, well its win-win for me.

If I don't notice the blur I don't notice the blur. That is no different than switching back to 120hz and noticing the obvious difference, or switching from IPS to TN and noticing the shimmering crud. You become accustomed to what is on your desk.

You seem to be missing you're speaking in preferences not absolutes. I'm not trying to change your mind, not sure why you think you can change mine.

Quality colour and consistency = IPS/IGZO/VA
Quality response time and refresh rate = TN

Pick your poison both have their drawbacks.

 

[Mand]

Quality colour and consistency = IPS/IGZO/VA
Quality response time and refresh rate = TN

Pick your poison both have their drawbacks.

The point I was trying to make is that response time and refresh rate affect color and consistency for anything with a moving image. If you're doing editing work where you're looking at still frames, then yeah, IPS all the way. But that advantage drops off dramatically as soon as anything starts moving.

 

[Termie]

Interesting and informed debate here from two seasoned members.

Bunnyfubbles - may I ask which LMB monitors you refer to? As the Swift is not yet out, are you referring to the BenQ in your sig? Is that the only model that has universal LMB? And is Lightboost the Nvidia-specific equivalent?

I've enjoyed gaming on my 2713HM, but will be picking up a 1080p 144Hz monitor soon. The Swift really isn't in the cards, so I'm thinking Asus or BenQ, as you've now convinced me that the AOC and Philips that recently hit the market may be missing an important feature (i.e., LMB).

 

[poohbear]

Why is it so hard to make an IPS with 120hz &/or gsync @ 1440p? Is it a technical limitation?

Im sure there are excellent TN panels, but the viewing angles totally turn me off. I sometimes like to sit back on my bed in my room & watch movies....with a TN panel the angle would make the movie unwatchable.

 

[Termie]

Why is it so hard to make an IPS with 120hz &/or gsync @ 1440p? Is it a technical limitation?

It has to do with the amount of data being processed - you have higher color quality with IPS, higher resolution with 1440p, and higher refresh at 120Hz. Getting a monitor to do all three is tough - see the separate thread on the Overlord for insights into its overclocked IPS 1440p monitor: http://forums.anandtech.com/showthread.php?t=2391576

 

[Grooveriding]

Why is it so hard to make an IPS with 120hz &/or gsync @ 1440p? Is it a technical limitation?

Im sure there are excellent TN panels, but the viewing angles totally turn me off. I sometimes like to sit back on my bed in my room & watch movies....with a TN panel the angle would make the movie unwatchable.

I don't believe it is a technical limitation. We've seen IPS screens with custom PCBs overclock to 120hz. There is also a 120hz VA screen with its own implementation of a low motion blur mode from Eizo.

http://www.tftcentral.co.uk/reviews/eizo_fg2421.htm

It performs much like high speed TNs without the shimmering and low image quality and has a response time much better than other VA screeens and similar to IPS response rates. It's $599 for just a 1080p screen though. I feel like 1080p is starting its trip to being a resolution of the past with the push for 4K and more affordable 1440p screens available. It would be nice if Eizo made some other offerings in larger resolutions.

I think what is holding back monitor manufacturers from making one is cost and level of interest for one in the market. Until this monitor all we've seen are 1080p 120/144hz TN screens. The price of a factory manufactured 120hz IPS screen in 1440p or 1600p from a major monitor vendor would probably be prohibitive for most.

 

[Mand]

Why is it so hard to make an IPS with 120hz &/or gsync @ 1440p? Is it a technical limitation?

Yes, it's a technical limitation, one driven by liquid crystal chemistry and materials properties.

There are physics reasons why we can't get the best of all worlds. The material properties of the things involved in the tech are often contradictory - by improving one aspect, you degrade another. For something like response time, there are a number of factors that go into it. Viscosity of the material, susceptibility to electric fields (how much it moves for a given voltage), how quickly the crystals relax after the electric field is turned off, all of these are intrinsic material properties based on the specific chemical structure of the liquid crystals used. Things like substituting hydrogen for fluorine in one part of one component of the overall mixture can have a significant effect, but almost never in the "does good things for all properties." To take one specific example, you can use crystals that have a higher susceptibility (move faster when the same voltage is applied), but that usually means higher viscosity as well (more force required for the same movement).

The different panel types are an effort to explore the edges of the parameter space, in ways that let us pick which properties we're most interested in and make concessions on the rest. Believe me, if there were a perfect liquid crystal mixture that would get us IPS color at TN speeds, we would already be using it.

There are IPS displays that quote 120 Hz refresh, yes. But, just because you're issuing commands at 120 Hz does not mean that the crystals are actually getting to their required orientation in time to sit there long enough to reproduce the image with fidelity. Unfortunately, this behavior is rather difficult to measure and characterize, but can still lead to an impact in usage conditions.

Now, like any technical limitation, there are hard limits and there are soft limits. Organic chemists are constantly looking for new formulations for liquid crystals, and it's entirely possible they will find something new that pushes out the edges of the parameter space. There is not a hard limit to this, only things that make progress subject to diminishing returns.

 

[kasakka]

Why is it so hard to improve on TN viewing angles though? I think TN can deliver quite decent color nowadays but viewing angles seem to be fine only on some laptop sizes. Is it the bigger the display, the harder it is to get rid of the color/gamma shifting?

They have improved a little over the years but still quite obviously bad.

Same for VA and it's black crush.

 

[n0x1ous]

Im having a hard time trying to decide what trade off to make. I have a 1080p 144hz TN and enjoy it for gaming (which is what I primarily do on my PC) but I also dabble with Lightroom and obviously its terrible for that. Im ready to move beyond 1080p however, but dont wan't to miss the color/Viewing Angles of IPS nor the smooth blur free motion of TN.

Whats the best compromise for 75% gaming 25% photo work @ either 1440p or 4k?

I just want a 4K IPS 120hz (96 would be fine) with Gsync/Freesync and more than 1 displayport input. OEM's - build it and we will come!

 

[BrightCandle]

If you look at high quality reviews of IPS monitors (like that on tftcentral) you will find the switch time of an IPS pixel is usually above 12ms, but the range depending on how far it has to change is anywhere up to about 24ms. If we wanted to guarantee that the pixel had fully completed changing colour, IPS screens would actually only run at about 40 hz. Most of the time they can do a little better than 60hz worth of switch, although it really depends on the type of transition. So you can overclock the panel all you like its still going to switch the pixels at a similar speed and thus the pixel wont reach the colour its meant to be before the next frame comes along.

On the other hand the top TN panels these days can reach 1-4ms for a complete transition, they are actually limited by the chip as they could in theory support 250 hz already. But what you want to happen is the pixel switches and then it holds that colour for a while, thus we get to see the proper image for the grand majority of the time we are looking at the image. It still has persistence issues with the eye but it removes the motion blur, which is really another way of saying the pixel didn't actually represent the colour it was meant to be because that is what blur is, its a bleed from a previous image impacting the colour of the current image.

So the issue with IPS monitors is that when you calibrate them and show the colour quality what you are doing is testing them on a static image, something they are very good at. But when we look at a game that is in motion, with pixels going through large transitions of colour the pixels are taking a large amount of time to switch, even at 60hz they don't spend even half their time at the colour they are meant to be. Regardless of how great their static colour quality might be they aren't showing that colour quickly enough or for longer enough before the next frame arrives. Overclocking helps in some scenarios just because you are seeing the updates, but you'll also typically have a shadow following around a high contrast object like a person or mouse pointer because the pixels still aren't making the transition fast enough. Overclocking reduces the latency, it can reduce certainly improve the update rate of the image but it also increases the problem of colour accuracy under motion with potentially multiple screens worth of "bleed" into the current one.

I have seen a few IPS monitors with high quality AMA start to drive below 10ms at best, but at worst they are still in the 16ms range. Hence IPS panels are designed at 60hz, because its the best they can just about do. Realistically they aren't holding the colour long enough for 60hz to look good.

The pulsing backlight of the lightboost 2 monitors (such as the Benq in my sig) means that we can have the backlight dark while the pixels transition, then flash brightly to show the image and then darken again while we transition the pixels. This removes almost all of the motion blur associated with the panel by rarely showing the pixels in transition and it also alleviates the problem of our eyes persisting an image that is effectively solid for 8/16ms and then changing. The brain seems quite happy to fill in the blank bits and show a solid changing image to us under motion. Its basically what CRTs used to do and its the reason they didn't really have bleed through like LCDs do of the previous image.

The ROG screen is one of these 1-2ms TN screens, but its also 8 bit colour and has a very accurate under calibration. Its also important to understand one of the things that makes IPS screens good is the colour gamut, they use real 8 bit or even 10 bit colour gamuts with good colour points for reaching the entire standard. This is one thing the ROG gets about right, the range of colour is 8 bit so its accurate on static images and in addition its full SRGB gamut like the IPS monitors its compared to, so it will produce a very IPS like image. But without anywhere near the same bleed. This just isn't a typical TN panel, its got IPS like qualities in its colour accuracy and its got TN like qualities in its motion blur. In essence its a fantastic combination. It might say TN on the box but the only remaining drawback it holds from TN is the colour shift when sat off angle. It would make a dreadful TV but its not as big a problem for a monitor.

When you compare to an overclocked IPS the dV of the colours when in motion will be dramatically better on the ROG or any of the high 144hz TN screens. We can see that in the travel car images on tftcentral's review, all that halo or shadow of the previous image is inaccuracy, its dV away from the image its meant to be displaying. If you scale that up to a complete game image and every pixel showing this sort of effect it makes a dramatic difference to the quality of the image.

I used to play with a Dell 2410, which arguably was one of the best low blur IPS monitors of recent years, it was highly recommended here and indeed it reviewed well just about everywhere. It had great contrast, low dV and a decent overdrive, it was low motion blur for an IPS. Yet I struggled to move and shoot in FPS games with it because I couldn't see properly. For over a year I struggled in games moving and shooting and I just couldn't understand what was going wrong, my eyes/brain just weren't telling me there was a problem but I could see it in my K/D and loosing regularly when moving and shooting. Then I gamed on a 144hz on a show PC and I immediately understood the issue, bought one and am very happy with the difference in made. I follow these monitor reviews in detail and it really does take seeing the difference in action to understand just how important that motion blur image is and what it really means. It means the monitor isn't displaying the image its meant to, dramatically impacting the dV from the colours the game is requesting. The problem with that is that under high motion it looks really bad, its smudged its blurry and its hard to pinpoint the right areas on your target. My brain can't track people properly under those circumstances, it can only really shoot at them when they and I are mostly static.

IPS monitors are good for low movement static things like office work, image editing and workstation like activities. Maybe its OK in some game genres as well, but in most cases it will produce a lower quality image (in the sense the colour accuracy from what it should be displaying) than a high quality TN panel. I wish reviewers would do more than just show motion blur, but instead show just how far out the image is from what it should be. That is the real test.

 

[bunnyfubbles]

Interesting and informed debate here from two seasoned members.

Bunnyfubbles - may I ask which LMB monitors you refer to? As the Swift is not yet out, are you referring to the BenQ in your sig? Is that the only model that has universal LMB? And is Lightboost the Nvidia-specific equivalent?

I've enjoyed gaming on my 2713HM, but will be picking up a 1080p 144Hz monitor soon. The Swift really isn't in the cards, so I'm thinking Asus or BenQ, as you've now convinced me that the AOC and Philips that recently hit the market may be missing an important feature (i.e., LMB).

the advent of LMB on PC came around as soon as someone discovered that the LightBoost feature nVidia implemented to help reduce blur and ghosting in 3D mode could be tricked into operating all the time, even for 2D applications.

I bought my XL2420T back in 2012 because it was just a very fast and feature rich 120Hz monitor that improved upon the XL2410T model that I had grown to love the previous 2 years, the 2420T's ability for LMB was only later discovered to be a bonus and not officially supported by either BenQ or nVidia.

Basically, until recently we've had to turn nVidia 3D read monitors into our own LMB monitors thanks to LightBoost, which was messy early on as it involved registry tweaks, but this has since been made very easy - and also works on AMD GPUs - with the 3rd party Strobelight tool by ToastyX - http://www.monitortests.com/forum/Thread-Strobelight-LightBoost-Utility-for-AMD-ATI-and-NVIDIA.

However newer models are being produced with newer LMB techniques (ULMB on G-Sync, Turbo 240 on Eizo's FG2421, BenQ Blur Reduction on their Z series) specifically intended to be used to reduce all motion blur (as LightBoost was developed to help push nVidia 3D, which is pretty ironic in that its now far more popular for its effect outside of 3D, and that nVidia would have been better off pushing the feature for everyone and not just 3D users, although perhaps they didn't because it is a feature that can be produced even for AMD users, unlike 3D)

blurbusters.com is my current go-to source, and a good list of monitors can be found here - http://www.blurbusters.com/faq/120hz-monitors/

I suppose if I had to buy now (assuming the ~$600 1080p Eizo is equally out of the question as the $800 1440p ASUS) I'd be interested in the BenQ XL2420Z first, as the BenQ Blur Reduction is supposedly very good and the ASUS VG248QE second (although if there was a more affordable/official G-Sync version, i.e. not a DIY option, it would probably be my first choice)

 

[Termie]

snip

Awesome info BrightCandle - I've never read a clearer description of the ins and outs of high refresh rate monitors.

...

I bought my XL2420T back in 2012 because it was just a very fast and feature rich 120Hz monitor that improved upon the XL2410T model that I had grown to love the previous 2 years, the 2420T's ability for LMB was only later discovered to be a bonus and not officially supported by either BenQ or nVidia.

Basically, until recently we've had to turn nVidia 3D read monitors into our own LMB monitors thanks to LightBoost, which was messy early on as it involved registry tweaks, but this has since been made very easy - and also works on AMD GPUs - with the 3rd party Strobelight tool by ToastyX - http://www.monitortests.com/forum/Thread-Strobelight-LightBoost-Utility-for-AMD-ATI-and-NVIDIA.

However newer models are being produced with newer LMB techniques (ULMB on G-Sync, Turbo 240 on Eizo's FG2421, BenQ Blur Reduction on their Z series) specifically intended to be used to reduce all motion blur (as LightBoost was developed to help push nVidia 3D, which is pretty ironic in that its now far more popular for its effect outside of 3D, and that nVidia would have been better off pushing the feature for everyone and not just 3D users, although perhaps they didn't because it is a feature that can be produced even for AMD users, unlike 3D)

blurbusters.com is my current go-to source, and a good list of monitors can be found here - http://www.blurbusters.com/faq/120hz-monitors/

I suppose if I had to buy now (assuming the ~$600 1080p Eizo is equally out of the question as the $800 1440p ASUS) I'd be interested in the BenQ XL2420Z first, as the BenQ Blur Reduction is supposedly very good and the ASUS VG248QE second (although if there was a more affordable/official G-Sync version, i.e. not a DIY option, it would probably be my first choice)

More awesome info, bunnyfubbles. Was about to go for the Asus, but maybe I'll spring for the BenQ.

 

[bunnyfubbles]

If I don't notice the blur I don't notice the blur. That is no different than switching back to 120hz and noticing the obvious difference, or switching from IPS to TN and noticing the shimmering crud. You become accustomed to what is on your desk.

You seem to be missing you're speaking in preferences not absolutes. I'm not trying to change your mind, not sure why you think you can change mine.

Quality colour and consistency = IPS/IGZO/VA
Quality response time and refresh rate = TN

Pick your poison both have their drawbacks.

yup, ignorance is bliss, but I know I'm both better and worse off for having noticed the difference

 

[kasakka]

I suppose if I had to buy now (assuming the ~ 1080p Eizo is equally out of the question as the 1440p ASUS) I'd be interested in the BenQ XL2420Z first, as the BenQ Blur Reduction is supposedly very good and the ASUS VG248QE second (although if there was a more affordable/official G-Sync version, i.e. not a DIY option, it would probably be my first choice)

Isn't the ASUS VG248QE G-SYNC exactly that, same monitor with built-in G-Sync?

Damn ASUS has confusing model naming, they are all so close.

 

[Grooveriding]

yup, ignorance is bliss, but I know I'm both better and worse off for having noticed the difference

I don't know that talking yourself into accepting lower quality panels to accommodate your perceptions is necessarily making you worse off. Everyone finds the value that fits and works for them and it's a matter of what you have to settle with that is going to have to be a fit for you.

I don't mind waiting for more improvements to come to the IPS/IGZO panels, and in the mean time will continue to use them for what they provide. Once GPUs have caught up, hopefully next year, there is again no way I'll pass up gaming on a 4K 32" IGZO against an option with lower fidelity but better motion. So even if there winds up being some good 1440p IPS options with 120hz I will still find myself preferring a higher resolution and better PQ option.

 

[bystander36]

I don't know that talking yourself into accepting lower quality panels to accommodate your perceptions is necessarily making you worse off. Everyone finds the value that fits and works for them and it's a matter of what you have to settle with that is going to have to be a fit for you.

This is where you got it all wrong, and why people are arguing with you.

IPS panels are not higher quality.
TN panels are not lower quality.

They both have different advantages and weaknesses.

TN panels are higher quality with a changing image.
IPS panels are higher quality with a static image.

One is not inherently superior. They have their moments. For most gaming, a quality TN panel is generally superior, but under some conditions, that may not always be true.

 

[Mand]

Why is it so hard to improve on TN viewing angles though?

Because of how the crystals are oriented, and how they block light.

LCs are polarization devices. TN stands for twisted nematic, which describes the physical configuration of the crystals that perform the switching. Nematic means "threadlike" and looks like this:

This results in the liquid crystal no longer being isotropic: now, its optical properties depend on which direction the light is going, and which orientation the light is polarized in.

Twisted nematic refers to setting up a series of these structures so that they point in a slightly different orientation as you go down, the result is a spiral. When in this configuration, they will rotate the polarization of linearly polarized light just a bit with each step down the spiral, through the full twist of 90 degrees (below left):

By putting linear polarizers above and below, you can make it so that the light that passes through the TN structure is aligned so that it will pass through the second polarizer and come out to your face.

The "opaque" state is when the TN structure is disrupted. The crystals are not in their precise arrangement, and do not provide the required rotation of the polarization (above right). The result is that you have two crossed polarizers, and the light is blocked.

You can control the degree to which the TN structure is present, and by doing so change the opacity of the LC cell. This is how you get your 6-bit or 8-bit levels within each pixel.

TN's angular issues come from the fact that the TN structure only works correctly if the light is hitting it directly from normal incidence. If you move your head off-axis, you're seeing light that didn't properly go through the TN spiral, and so is only partially affected by the TN structure. This means that any light that goes off to the sides isn't affected by the right level of opacity in the LC cell. With each pixel being made up of individual color subpixels, with each one having a different opacity in order to generate color, each channel is affected differently by moving off-axis, which results in the strange color shifts. In early LCDs, this ended up being a full contrast reversal with only a slight angular offset - more recently, improvements in LC cell design have made it so that this effect is minimized as much as possible.

But it's still something fundamental to TN, something that you can only get away from fully by not using a twisted nematic structure in your LC cell.

 

[Grooveriding]

This is where you got it all wrong, and why people are arguing with you.

IPS panels are not higher quality.
TN panels are not lower quality.

They both have different advantages and weaknesses.

TN panels are higher quality with a changing image.
IPS panels are higher quality with a static image.

One is not inherently superior. They have their moments. For most gaming, a quality TN panel is generally superior, but under some conditions, that may not always be true.

I'm not seeing any arguing here, just differences of opinion.

Because of how the crystals are oriented, and how they block light.

LCs are polarization devices. TN stands for twisted nematic, which describes the physical configuration of the crystals that perform the switching. Nematic means "threadlike" and looks like this:

This results in the liquid crystal no longer being isotropic: now, its optical properties depend on which direction the light is going, and which orientation the light is polarized in.

Twisted nematic refers to setting up a series of these structures so that they point in a slightly different orientation as you go down, the result is a spiral. When in this configuration, they will rotate the polarization of linearly polarized light just a bit with each step down the spiral, through the full twist of 90 degrees (below left):

By putting linear polarizers above and below, you can make it so that the light that passes through the TN structure is aligned so that it will pass through the second polarizer and come out to your face.

The "opaque" state is when the TN structure is disrupted. The crystals are not in their precise arrangement, and do not provide the required rotation of the polarization (above right). The result is that you have two crossed polarizers, and the light is blocked.

You can control the degree to which the TN structure is present, and by doing so change the opacity of the LC cell.

TN's angular issues come from the fact that the TN structure only works if the light is hitting it directly from normal incidence. If you move your head off-axis, you're seeing light that didn't properly go through the TN spiral, and so is only partially affected by the TN structure. This means that any light that goes off to the sides isn't affected by the right level of opacity in the LC cell. With each pixel being made up of individual color subpixels, with each one having a different opacity in order to generate color, each channel is affected differently by moving off-axis, which results in the strange color shifts. In early LCDs, this ended up being a full contrast reversal with only a slight angular offset - more recently, improvements in LC cell design have made it so that this effect is minimized as much as possible.

But it's still something fundamental to TN, something that you can only get away from fully by not using a twisted nematic structure in your LC cell.

This is awesome! :thumbsup: