**The Massive TFT Sticky - FAQ, Links and Buyers Guide**

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It’s been a long time since the original TFT sticky was created in November 2003, but it has been regularly updated since with new information, user opinions and guides each year. I thought it was time for a new guide with new information. Thanks again to the members of OcUK for all their comments and opinions, credited and quoted below. Baddass

For a lot of information about TFT specs, terms, technology and all these guides and more, visit my site at www.tftcentral.co.uk

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Index:

Buyers FAQ and Guide:

  • What Should I Look For In The Quoted Specification?
  • What Is the Best Panel Technology To Get?
  • Should I Be Worried About Gaming Performance?
  • Which Video Interface Connection Should I Use?
  • Should I Worry About 6-bit vs. 8-bit vs. 10-bit Panels?
  • What Does a Monitors Colour Gamut Mean?
  • Should I be worried about monitor flicker?
  • What's The Best Way To Clean a TFT Screen?
  • What's The Situation With Dead Pixels?
  • So Which Is The Best TFT To Get?

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Specifications:
  • LCD and TFT
  • Aspect Ratio
  • Resolution
  • Response Time
  • Brightness
  • Contrast Ratio
  • Viewing Angles
  • Pixel Pitch

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Terms, Features and Useful Guides:
  • Panel Technologies Explained
  • Monitor Calibration and ICC Profiles
  • Input Lag
  • Dynamic Contrast
  • Colour Gamut
  • Colour Depth
  • Pulse Width Modulation (PWM)
  • Blur Reduction

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Monitor Review Sites:

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Monitor News:

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Useful Links:
 
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Man of Honour
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Buyers FAQ and Guide:


Q. What Should I Look For In The Quoted Specification?

The first thing to realise when buying a new screen is that you can't always rely on quoted specifications. These are often exaggerated for marketing purposes, and are commonly based on different measurement techniques and varying benchmarks between each manufacturer. As a guide and general rule of thumb:

  • Resolution is an important consideration for various reasons. You need to consider the size of the screen, whether you will need to use operating system scaling or not (e.g. for Ultra HD or 4K resolutions) and whether your graphics card can support the resolution for your uses effectively (e.g. high demand on the system for gaming at 4K resolution). Read about resolution in more detail in our specs section below.
  • The lower the response time the better. Be aware of ISO response time figures and grey to grey (G2G) transition figures as you will need to understand the difference. Screens with a G2G quoted response time use ‘Response Time Compensation’ (RTC) technologies, sometimes referred to as ‘overdrive’. These technologies are used to boost pixel response times and in practice can make quite a lot of difference. This is particularly important with non-TN Film panels (i.e. IPS, PVA, MVA etc). Overall response times TN Film > IPS –type > VA-type
  • The higher the contrast ratio, the better. This will also help indicate the black depth of the screen and how well the screen can handle differences between light and dark content. Be wary of dynamic contrast ratio (DCR) figures being quoted nowadays and you will need to understand what the difference is between those and the ‘static contrast ratio’. Nowadays you will see static contrast ratio figures ranging in to the millions:1 in some cases. DCR figures are massively exaggerated and rarely useable in practice. Make sure you understand which contrast ratio figure is being quoted in a spec and ideally read a review where it is really tested. Overall with static contrast ratio typically VA > TN Film > IPS
  • The wider the viewing angles the better. Be wary of how they calculate their figures. Sometimes they will try sneaking things like listed them when CR > 5 instead of when CR > 10 to inflate their numbers. Again real life performance might not match quoted specs. You will normally see TN Film panels listed with a 170/160 viewing angle (a classic indication that the screen is using TN Film technology by the way). IPS-type and VA-type panels will normally feature a 178/178 viewing angle spec, but in reality the performance does vary. As a general rule of thumb, viewing angles IPS-type > VA-type > TN Film.
  • The higher the refresh rate, the better the screen would be for gaming generally. Refresh rate has a direct impact on motion clarity and frame rate support for the screen. Most high refresh rate panels are 120 or 144Hz natively which is a significant improvement over 60Hz standard refresh rate panels. Keep an eye out for "overclocked" refresh rates as well with some manufacturers boosting the natively supported refresh rate higher. Results of that overclock will vary so try and check out reviews before you assume it will offer further improvements.
  • If you're a gamer then look out for Variable Refresh Rate (VRR) technologies which will significantly improve fluidity in gaming and avoid stuttering, tearing or lag associated with older Vsync technologies. At the moment your choice depends on your graphics card vendor, either AMD FreeSync or NVIDIA G-sync.

I would really recommend reading further into the details about monitor specs before you make your purchase so you can understand what they infer about the monitors performance characteristics.


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Q. What Is the Best Panel Technology To Get?

A very important thing to consider is what panel technology the screen uses you are interested in buying. While specs may look similar on paper, performance may vary quite considerably between the models due to the underlying panel technology used. The most common technologies used in the desktop monitor market are TN Film, IPS (and similar variants like PLS and AHVA) and VA. These are all produced by a range of panel manufacturers and offer a variety of strengths and weaknesses. There is a reasonable amount of talk about panel technologies with many people quick to jump on a bandwagon and claim one is superior to another. To be honest, they all still have their place in the modern market, and due to their different characteristics, can play a key part in finding the right monitor for your use.

There are various generations of each technology as well, and different manufacturers have slightly different names for their versions. Look out for

  • TN Film (Twisted Nematic + Film) = pretty uniform in naming, developed by many manufacturers including all the larger suppliers.
  • IPS (In Plane Switching) = S-IPS, H-IPS, e-IPS, AS-IPS, AH-IPS, p-IPS, generally all developed by LG.Display
  • MVA (Multi-domain Vertical Alignment) = S-MVA, P-MVA, AMVA, generally developed by AU Optronics and some from Chi Mei Innolux (formerly CMO)
  • PVA (Patterned Vertical Alignment) = S-PVA, cPVA, SVA, a Samsung technology exclusively manufactured by them but rarely used nowadays. Their equivalent to MVA
  • PLS (Plane to Line Switching) = S-PLS, a Samsung technology exclusive to them and very similar to LG.Display’s IPS in performance and can therefore be called an “IPS-type” technology
  • AHVA (Advanced Hyper-Viewing Angle) = developed by AU Optronics as another alternative to LG.Display’s IPS, very similar again and so can be called “IPS-type”

For more information about panel technologies, see this detailed article which is often updated.


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Q. Should I Be Worried About Gaming Performance?

Generally nowadays with all the ultra-low response time models available, ghosting caused by slow pixel response times is just not an issue for the majority of users. Performance has improved significantly over the years and blurring and ghosting has been largely eliminated on the faster displays. The use of RTC technologies (overdrive) significantly helps improve response times and speed up pixel transitions. This is particularly important on IPS/VA type displays which can be very slow where RTC is not used. Look out for response time specs quoted with a “G2G” (grey to grey) response time as that should indicate the use of overdrive technologies.

Nowadays screens supporting high refresh rates (120Hz+) input frequencies are becoming more and come common, and these can help reduce motion blur and ghosting and improve gaming performance considerably. They are also able to support higher frame rates than traditional 60Hz displays and some are also capable of supporting 3D stereoscopic content through active shutter glasses. Do be careful of assuming that a screen advertised as supporting 3D is in fact able to support 120Hz though, as some 3D models do not support this and instead use passive methods to produce the 3D effect (see here for more info on 3D technologies). Refresh rate of the panel does have a direct impact on motion clarity and for optimal gaming performance you will want to consider those high refresh rate displays above 60Hz.

Ghosting and motion blur perception may also depend on how susceptible you are as a user, as one person may see no ghosting, another may see lots on the same panel. The best bet is to try and see a TFT in action in a shop and see for yourself, if that’s not possible you will have to settle for the opinions of other users and take the plunge! Also be careful to get an idea of real life performance in practice, and don’t just rely on quoted specs. While they are often a good rough guide to the gaming performance, they are not always reliable.

One area which cannot be eliminated fully through response time improvements is perceived motion blur. This is related to how the human eye tracks movement on hold-type displays like LCD’s. In recent years several methods have been used to help provide improved motion blur for users. Models featuring LightBoost backlights for 3D gaming were found to be “hackable” to bring about motion blur benefits through the use of their strobed backlight system. Other displays have now introduced native strobed backlights to offer similar benefits. Look out for models with Motion Blur Reduction backlights like the BenQ XL2420Z / XL2720Z (Blur Reduction mode), Eizo Foris FG2421 (Turbo 240) and Asus ROG Swift PG278Q (ULMB) for instance. ULMB as a feature is common on NVIDIA G-sync enabled displays where high refresh rate is used.

Have a read here about response times if you are unsure about what specs mean or want more information. Generally modern TN Film panels will offer the fastest response times, and often also support 120Hz input frequencies for 3D support / extended frame rates. Look out for models with a quoted “G2G” response time indicating they also use overdrive which can really help in practice. Modern IPS-type panels can also be very fast where overdrive is applied well, so again look for “G2G” figures. High refresh rate IPS panels are also becoming more common which helps improve motion clarity further. Other technologies like PVA and MVA are unfortunately quite slow in practice by modern standards, even where overdrive or high refresh rates are used. Check reviews to be sure of an individual screens performance wherever possible.


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Q. Which Video Interface Connection Should I Use?

As a rule of thumb, it would normally be best to use the digital video connection end to end to connect your device to your monitor. For a PC, this would commonly be DisplayPort, HDMI or DVI which offer a pure digital end to end connection between the graphics card and the monitor. DisplayPort is needed to run the high resolution/high refresh rate panels so you will need to ensure your graphics card has a DP output. Some screens or cards use Mini DP instead of the full size version, but that is simply a different size connection and can be easily inter-changed with “normal” DisplayPort. Cables which are DP at one end, and Mini DP at the other are common and simple to use.

HDMI and DisplayPort are also common digital connections now being offer, but unlike DVI are also capable of carrying audio as well as video. The PQ should not be any different between DVI and HDMI/DisplayPort in theory as long as no additional video “enhancements” are applied when using one over the other. Bandwidth requirements will vary so this might influence which tyupe you need to use depending on the screen resolution and refresh rate.



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Q. Should I Worry About 6-bit vs. 8-bit vs. 10-bit Panels?

There is a lot of talk about colour depth on TFT screens, now more than ever with the emergence of 6-bit IPS and VA panels. At one time TN Film was the main 6-bit technology but today that is no longer the case. It's important to put this into perspective though, and not jump on the bandwagon of 8-bit being much, much better than 6-bit. Or even 10-bit being much better than 8-bit.

An 8-bit display would offer a colour palette of 16.7 million colours. They offer a 'true' colour palette, and are generally the choice of manufacturers for colour critical displays over 6-bit panels. On the other hand modern 6-bit screens use a range of Frame Rate Control (FRC) technologies to extend the colour palette from 262,144 colours to around 16.7m. In fact on many modern panels these FRC are very good and in practice you’d be hard pressed to spot any real difference between a 6-bit + FRC display and a true 8-bit display. Colour range is good, screens show no obvious gradation of colours, and they show no FRC artefacts or glitches in normal everyday use. Most average users would never notice the difference and so it is more important to think about the panel technology and your individual uses than get bogged down worrying about 6-bit vs. 8-bit arguments.

Manufacturers use 6-bit panels (+FRC) to help keep costs lower. As a result, a modern range of IPS and VA panels is also now produced which use 6-bit colour depth (+FRC) instead of true 8-bit colour depths. At the other end of the scale there are also some panels which can offer support of 10-bit colour depth. Again these come in two flavours, being either a true 10-bit panel (quite rare and expensive) offering 1.07 billion colours or an 8-bit panel with an additional FRC stage added (1.07 billion colours produced through FRC). The 8-bit +FRC panels are of course more common and will often be used to offer “10-bit” support in desktop displays. With 10-bit colour though there is also an additional consideration which is whether you would ever even be able to use this in your work. You can also only make use of this 10-bit support if you have a full end-to-end 10-bit workflow, including a supporting software, graphics card and operating system which is still very rare and expensive for most users. So for many people the use of a 10-bit capable panel is rather meaningless.

Note: Colour depth in this regard should not be confused with colour gamut, see below.



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Q. What Does a Monitors Colour Gamut Mean?

Colour gamut or colour space refers to the range of colours which the screen is capable of showing, in relation to a reference colour space. The human eye can see a certain range of colours which is represented by a CIE Diagram. This shows the full range in reds, greens and blues which the eye can see. Within that massive range there are various reference colour spaces, the most common of these being the sRGB space. There are also other reference colour spaces such as the NTSC and Adobe RGB which are often used in specifications nowadays and may be used in certain workflows. These are larger colour spaces than sRGB, so manufacturers needed a way to quantify the changes they had made.

The colour space / gamut capability of a monitor is not determined by the panel technology, but rather by the backlight technology being used. Traditional screens used standard CCFL backlighting which (for simplicity of comparison here) offered a colour space covering the sRGB space almost exactly, which equates to about 72% of the popular NTSC reference space. With backlighting technology changes and improvements, some screens then started to use WCG-CCFL (Wide Colour Gamut CCFL) backlighting which can offer an extended gamut covering commonly 92% - 102% of the NTSC reference space. This allowed them in turn to cover most of the Adobe RGB colour space, which is wider than sRGB. Other backlighting technologies like W-LED (White LED) are now very common, and at the moment cover the sRGB space (~68 – 72% NTSC). Wider gamut LED backlights like GB-r-LED for instance offer wide gamuts comparable to older WCG-CCFL, but with energy and environmental benefits of LED backlights. They are commonly advertised as supporting the Adobe RGB space instead of NTSC figures as that is more commonly used nowadays. Screens where Adobe RGB coverage s discussed give an indication of a wide colour gamut.

While a larger colour space might sound like a good idea, it's not always for everyone. You need to keep in mind what content you will be viewing on the screen, and what colour space that content is based on. Since sRGB is very common and the standard for many things like Windows and the internet, viewing sRGB content on an extended gamut screen can cause oversaturation of colours and an unrealistic stretching of the colours. Reds and greens in particular can appear quite 'neon' and some users do not like this. The smaller colour space of the content is, as a very crude description, 'stretched' over the larger colour space of the monitor. On the other hand, some applications are colour space aware (e.g. Adobe Photoshop) and so if you are working with extended gamut content, you will prefer an extended gamut screen. I'd certainly recommend reading more into this as it is only a brief summary here. Where a screen has an extended gamut, they sometimes provide an sRGB emulation mode which work to varying degrees. Handy if you might need to use it, but make sure the screen offers a decent performance when in this mode and that it works. At the end of the day, the choice of monitor might very well depend on the colour space you want to work with. For most average users a standard CCFL or W-LED backlit display with a standard sRGB gamut would probably be preferred.

See here for further information on gamut. There is also a more detailed and in depth article about colour spaces here.


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Q. Should I be Worried About Monitor Flicker?

Monitor flicker is a topic which has only really popped up within the last couple of years, mostly because of the arrival of LED backlights. As a brief background, for many years the brightness regulation of an LCD monitor has been controlled using a technique called Pulse Width Modulation (PWM). This technique basically turned the backlight on and off rapidly to allow for brightness reductions. As you lower the brightness setting in the OSD menu, the “off” period of the backlight is increased to bring about lower perceived luminance. This cycling can run at varying frequencies depending on the backlight system being used, from low frequencies like 140Hz (140 times per second) up to several thousand Hz.

With the arrival of LED backlights, the on and off flashing of the backlight on PWM-dimmed displays becomes more pronounced as the LED’s can turn off and on more quickly than older CCFL backlights. This affects a lot of users who can suffer from eye fatigue, headaches, eye strain etc (and sometimes even visible flicker) especially where frequencies are lower. As a result a lot of people try to avoid screens with PWM backlight dimming.

Some manufacturers are now actively providing flicker free displays, using a backlight dimming technique called Direct Current (DC) where PWM is no longer needed. This eliminated eye strain and other issues associated with PWM. Look out for monitors specifically advertised as flicker free if you are worried at all about this, or have suffered on other screens before. Some screens are not advertised as being flicker free, but may be found to be PWM-free from reviews.

See here for a comprehensive list of flicker free monitors.



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Q. What's The Best Way To Clean a TFT Screen?

The simplest and cheapest way to clean a TFT screen is with a slightly damp cloth; wipe off the left behind water with a towel or similar then smooth/dry completely with a yellow polishing cloth. Be careful not to use products such as toilet paper and kitchen roll as they contain lint and can leave scratches on your beloved screen! Cleaning solution from opticians and lint free clothes for lens cleaning are also very good.

For the perfectionist, there are also some very nice microfiber solutions available such as the ‘Cloth Addiction’ range.



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Q. What's The Situation With Dead Pixels?

Unfortunately dead pixels can be an issue on TFT screens as they are often developed during the manufacturing stage. For retail costs to be kept low the companies cannot afford to make all screens defect-free and check for dead pixels all the time. Pixels can be described in the following ways:

  • Fully dead - stuck on black of white
  • Dead Sub Pixel - Stuck on Red / Green / Blue permanently
  • Lazy - stuck on a colour, but sometimes can change. If the pixels are only lazy, there may be hope of reviving them. If they are fully dead, they will stay that way.

Dead pixels very rarely develop during use, unless you have a habit of poking the screen. If you are careful with the screen, hopefully you shouldn't develop any further pixel problems. To test for dead pixels, there is "Dead Pixel Buddy" program available. You can manually cycle through different full screen colours (black/white/red/green/blue) to check for dead or lazy pixels or rapidly cycle through all of the colours automatically to try and coax lazy sub-pixels back to life. Leave it running for half an hour, if you're lucky it can work!

If you want to ensure that you receive a pixel perfect screen (and who wouldn't at the kind of prices you are paying for the TFT!?!) then you can often pay for pixel checks from some online retailers. Beware though! Never buy a TFT from retailers who offer the pixel check without having the check done as you can be sure the screens they find to be non-perfect will be winging their way to the customers who don't have the check! The only other option to ensure you get a pixel perfect screen is to check out the panel in a shop in person, then you can see for yourself.....

If you find you have a dead pixel there is not a lot you can do unfortunately. If you have a certain number of dead pixels (usually at least 3 or a certain number centrally on the panel) then the manufacturer will replace the TFT for you, but the number of dead pixels needed before this happens varies between each manufacturer, so check with them before you order if you're concerned.

Some lazy pixels can be bought back to life occasionally. Playing some fast paced games for a while, and massaging / flicking the pixel area with a lint free cloth can sometimes help revive the lazy pixel, but not in all cases.

If you still have a dead pixel problem, can't bring it back to life and can't RMA it under warranty then you can sometimes return it to the stockist if you purchased it online. If you bought online you can take advantage of the "Distance Selling Act" which entitles you to return any item within 7 days as you were not present at the time of purchase. If you are not happy with your TFT you can return it at your cost of postage and often claim a refund or exchange. However, be aware that a lot of places will try and charge you restocking fees and they will almost certainly specify the goods must be packaged and in the same condition as when you received it, so be careful to package it back up nicely. Legally, if the stocker accepts the TFT back as a return governed by the Distance Selling Act, then they are NOT allowed to charge you a restocking fee as covered in the Government Regulations. This selling act is not widely advertised by retailers, but does exist if you really need to use it. You should only have to pay for postage to send it back to them.


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Q. So Which Is The Best TFT To Get?

This question pops up ALL the time! It really depends on what you want the TFT for, how much you want to pay etc. Performance varies with different panel technologies and with different specs. Check out the TFT Selector Tool which will hopefully help you decide on the screen which suits your needs. You also need to base your decision on the looks of the TFT, any extra functions which you might find useful, and the price.
 
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Specifications


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LCD and TFT
LCD stands for "Liquid Crystal Display" and TFT stands for "Thin Film Transistor". These two terms are used commonly in the industry but refer to the same technology and are really interchangeable when talking about certain technology screens. The TFT terminology is often used more when describing desktop displays, whereas LCD is more commonly used when describing TV sets. Don't be confused by the different names as ultimately they are one and the same. You may also see reference to "LED displays" but the term is used incorrectly in many cases. The LED name refers only to the backlight technology used, which ultimately still sits behind an liquid crystal panel (LCD/TFT).

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Aspect Ratio

The aspect ratio of a TFT is related to the ratio of the image in terms of its size. The aspect ratio can be determined by considering the ratio between horizontal and vertical resolutions. While a 20"/21" screen with 1600 x 1200 resolution is a 4:3 ratio, 17" and 19" models are 5:4 ratio since their native resolution is 1280 x 1024. Widescreen formats are now the norm, with 16:10 and 16:9 ratios, the latter generally used more for multimedia screens and in the LCD TV market. 1920 x 1200 resolutions (16:10) are available on some 24” desktop screens, while many 21 – 27” screens are 1920 x 1080 (16:9). Other higher resolutions are available in bigger screens including 2560 x 1440 and 3840 x 2160 in 16:9 aspect ratios. 2560 x 1600 is also available in 30” screens for a 16:10 aspect.


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Resolution

The resolution of a TFT is an important thing to consider. All TFT’s have a certain number of pixels making up their liquid crystal matrix, and so each TFT has a “native resolution” which matches this number. It is always advisable to run the TFT at its native resolution as this is what it is designed to run at and the image does not need to be stretched or interpolated across the pixels. This helps keep the image at its most clear and at optimum sharpness. Some screens are better than others at running below the native resolution. You cannot run a TFT at a resolution of above its native resolution. Make sure your graphics card can support the desired resolution of the screen you are choosing, and based on your uses. If you are a gamer, you may want to consider whether your graphics card can support the resolutions you will want to use to power your screen. Also keep in mind whether you are planning to connect external devices and the resolution they are designed to run at.

As a guide to the common resolutions available:
  • 15” – 1024 x 768
  • 17” – 1280 x 1024
  • 17" WS - 1280 x 768
  • 18” – 1280 x 1024
  • 18.5”WS – 1366 x 768
  • 19” – 1280 x 1024
  • 19” WS - 1440 x 900
  • 20” – 1600 x 1200
  • 20” WS – 1680 x 1050 and 1600 x 900
  • 21” – 1600 x 1200
  • 21" WS - 1680 x 1050
  • 21.5”WS – 1920 x 1080
  • 22" WS - 1680 x 1050 and 1980 x 1080 and 1920 x 1200
  • 23" WS - 1920 x 1080
  • 23.6”WS and 23.8”WS – 1920 x 1080
  • 24” WS – 1920 x 1200 and 1920 x 1080
  • 25”WS – 1920 x 1080
  • 26" WS - 1920 x 1200
  • 27" WS - 1920 x 1200 and 1920 x 1080 and 2560 x 1440
  • 28" WS - 1920 x1200 and 3840 x 2160
  • 30" WS - 2560 x 1600
  • 31.5”WS – 3840 x 2160


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Response Time

Response Time is the spec which many people, especially gamers, have come to regard as the most important. It's official ISO classified measurement refers to the time taken for a pixel to change from being black (off) to white (on) and then back to black. In practical terms, it refers to the speed of the pixels and how quickly they can change from one colour to another, and therefore how fast the picture can be redrawn. The faster this transition can change, the better, and with more fluid changes the images can change overall a lot faster. This helps reduce the effects of blurring and ghosting in games and movies which can result if response time is too slow. Generally, the lower the response time, the better.

Do not rely entirely on response time specs quoted by manufacturers as a be all and end all to the monitor’s performance. Different manufacturers have different ways of measuring their response time, and one 8ms panel might not be the same in real use to another 8ms panel for instance. Panel technology also plays a part here. However, response times can be treated a guide to the performance of the screen, and as a rule of thumb, the lower the better.

With the introduction of overdrive technologies (Response Time Compensation – RTC) the ISO point is not always the fastest transition any more, and so if a monitor has a response time quoted as “grey to grey / G2G” then you can be pretty certain it is using overdrive technology. Overdrive is widely used in the market to boost pixel transitions and it can have a noticeable effect on all panel technologies. It has been particularly important in the development of IPS and VA panels where traditionally response time was very slow. The manufacturers still want to quote the fastest response time of their panel and show the improvements they have made though, but be wary of this change away from the ISO standard of quoting response times. The ISO response times have hit a wall really with TN Film stuck at 5ms, IPS stuck at around 14 - 16ms and MVA/PVA stuck at about 12ms. However, with the introduction of overdrive technologies, the more important grey to grey transitions are now significantly improved, and response times of 6ms, 4ms and 2ms G2G are now common place.

Please see the following section regarding the technologies introduced with overdrive to help improve response times: <more info>


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Brightness

Brightness is a measure of the brightest white the TFT can display. Typically TFT’s are far too bright for comfortable use, and the On Screen Display (OSD) is used to turn the brightness setting down and control the intensity of the backlight. Higher brightness is good as it can be useful for dark scenes in games / movies where it might be difficult to distinguish between shades of grey. Brightness is measure in cd/m2 (candella per metre squared). Note that the recommended brightness setting for a TFT screen in normal lighting conditions is 120 cd/m2 so you need to keep in mind how well the OSD lets you adjust a screens brightness in practice.


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Contrast Ratio

The Contrast Ratio of a TFT is the difference between the darkest black and the brightest white. As a rule of thumb, the higher the contrast ratio, the better. The higher the contrast ratio, the stronger the colours will look and the better the range of dark greys will appear. The depth of blacks and the brightness of the whites are also better with a higher contrast ratio. When considering a TFT monitor, a contrast ratio of 700:1 is pretty moderate nowadays, but there are models which boast specs up to and over 1000:1. Be wary of quoted specs however, as sometimes they can be exaggerated. VA panel specs are generally the most reliable and accurate to reality when considering contrast ratio.

A good TN Film, IPS, PLS or AHVA panel should be able to reach around 1000:1 static contrast ratio, while MVA variants can reach typically up to 3000 – 5000:1.

Some technologies boast the ability to dynamically control contrast and offer contrast ratios in the millions:1 on paper! You need to understand the difference though between a static contrast ratio and a dynamic contrast ratio (DCR) and how they perform in practice. DCR’s are largely pointless on many screens and only really useable for some people for movies or games.


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Viewing Angles

Viewing angles are quoted in horizontal and vertical fields and often look like this in listed specifications: 170/160 (170° in horizontal viewing field, 160° in vertical). The angles are related to how the image looks as you move away from the central point of view, as it can become darker or lighter, and colours can become distorted as you move away from your central field of view. Gamma, contras and colour tone shifts are common and are evident to varying degrees. Because of the pixel orientation, the screen may not be viewable as clearly when looking at the screen from an angle, but viewing angles of TFT’s vary largely depending on the panel technology used.

As a general rule, the viewing angles are IPS / PLS > VA > TN Film. The viewing angles are often over exaggerated in manufacturers specs, especially with TN Film panels where quoted specs of 160 / 160 and 170 / 170 are based on overly loose measuring techniques. In reality, IPS and VA panels are the only technologies which can truly offer wide viewing fields. VA panels can show a contrast distortion as you move slightly away from a central point but from wider angles they are better than TN Film. While most people do not notice this anomaly, others find it distracting. IPS panels do not suffer from this and so are generally considered the technology with the widest viewing angles. TN Film panels typically have restrictive viewing angles, especially vertically.


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Pixel Pitch

Unlike on CRT’s where the dot pitch is related to the sharpness of the image, the pixel pitch of a TFT is related to the distance between pixels. This value is fixed and the same for all TFT’s which are the same size. This is because a 17” TFT for instance will always be the same 17” viewable area, and will always have the same number of pixels (1280 x 1024). Pixel pitch is normally listed in the manufacturers specification. Generally you need to consider that the 'tighter' the pixel pitch, the smaller the text will be, and potentially the sharper the image will be. To be honest, monitors are produced with a sensible resolution for their size and so even the largest pixel pitches return a sharp images and a reasonable text size. Some people do still prefer the larger-resolution-crammed-into-smaller-screen option though, giving a smaller pixel pitch and smaller text. It's down to choice and ultimately eye-sight.

To calculate the pixel pitch of a given monitor size and resolution, you can use this useful Pixel Pitch Calculator.
 
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Panel Type

There are a few main types of panel technology widely used in the TFT market. Their implementation is dependent on the panel size mostly as they vary in production costs and in performance.


TN film (Twisted Nematic + Film) - were the first panels to be used and are still widely implemented in many TFT’s today, especially mid to low end screens. They are also the primary choice for gaming screens. This is due to their low manufacturing costs largely. The main issue with TN Film panels is that they have restrictive viewing angles of up to a realistic range of about 140 horizontally. Vertical viewing angles are very poor generally and suffer from a characteristic colour inversion and darkening as you look from below. TN Film panels traditionally offer the fastest pixel response times, and with the implementation of Response Time Compensation (RTC), or 'overdrive' technologies, the grey to grey transitions have become even faster. Today, TN Film panels are used in the majority of gamer-orientated screens and are often used to break into new screen sizes, offering a cost effective way to provide larger screens without increasing the price too much. TN Film displays often support higher refresh rates as well of 120Hz+, and gaming models are often combined with extras such as 3D content support, Blur Reduction backlights and now also G-sync technology.


IPS (In Plane Switching) and variants (PLS, AHVA) – these are developed by LG.Display (formerly LG.Philips) primarily. They are known for their strong colour performance and stable viewing angles. They are also free of the off-centre contrast shift which is evident on VA matrices, and as such are commonly the choice of graphics and colour professional displays. Response times were traditionally behind those of TN Film and VA panel variants, but modern IPS panels using overdrive can offer very good response times suitable for a lot of people. Other manufacturers including Samsung and AU Optronics have begun to manufacturer their own equivalents to IPS, dubbed PLS and AHVA respectively.


VA (Vertical Alignment) - are the third type used in modern TFT’s. The early VA panels have been scrapped due to poor viewing angles, and in their place came the Multi-Domain Vertical Alignment (MVA) and Patterned Vertical Alignment (PVA) panels. These offer superior colour reproduction compared with TN Film, but not quite as good as IPS variants. They do however have the advantage of being able to show good black levels and viewing angles are also better than TN Film. There is a characteristic off-centre contrast shift detectable from VA matrices, but not everyone will notice this or find it a problem. One of the main improvement in recent times has been in responsiveness, with overdrive playing a key role again. MVA panels are still produced, primarily by AU Optronics (AMVA generation) while Samsung don’t really make their alternative PVA any more, concentrating on PLS instead.

For further information about panel technologies, see here



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Monitor Calibration

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Calibration of a new monitor is very important if you are hoping to experience the most accurate colour rendering the screen is capable of. When buying a new screen, it’s important to understand how it will perform out of the box at default settings and also what you may be able to achieve with some basic OSD calibration, or through hardware calibration tools.

At default settings, TFT screens commonly come with extreme brightness settings, and poorly configured colours leading to poor colour accuracy between what is requested, and what is actually shown on the screen. Other factors such as colour temperature, gamma, contrast and black depth can also be affected, and it is often only with some careful calibration that you can get the most out of your screen.

Calibration via software is possible, but can rarely lead to much real improvement in accuracy. It is handy however for setting up brightness and contrast levels and can at least get the screen feeling more comfortable in use. For some guidelines and tools for software calibration see here. Also, see Lagom.nl which is a very good and popular website for software calibration and tests.

For more advanced calibration of your screen you would need a hardware calibration tool, either a colorimeter or a more expensive spectrophotometer. However these can be quite expensive. The X-rite i1 Display Pro gets my recommendation for a versatile and accurate device if you are after a colorimeter. Note some older devices don’t work as well on LED backlights.

Another more crude option for your screen is to try using a calibrated ICC profile which has been produced by someone else (e.g. a review site). Often combining their saved profile and OSD screen settings can improve results on another model, but results will vary and are not guaranteed. The OSD settings are used to first of all establish an optimum hardware “starting point” which gives a good initial balance of the colour channels and a comfortable and optimum brightness and contrast. From there, profiling using a calibration device corrects gamma curves and optimises the grey balance and colour accuracy at a software level. It then creates a profile which is activated at the graphics card Look Up Table (LUT) level. So you can combine the recommended OSD settings with the ICC profile to see how it might look on your screen if you wish. You may need some ICC profile loader tool to load the profile properly when your PC starts.

For a database of settings and calibrated ICC profiles, see TFT Central ICC Profile Database



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Input Lag

This phenomenon is not always acknowledged across review sites, but is often the subject of discussion in enthusiast forums. The premise is that an LCD display shows a degree of lag between the image being sent to the screen from the graphics card, and what is actually shown on the panel. This “input lag” or “display lag” is noticeable in practice when comparing a TFT and CRT side by side in clone mode, and you can see that the image on the TFT is lagging a little behind the CRT in some tests. It also produces a feeling of lag for the user. The degree of this input lag varies from one screen to another. Its presence can be linked to screen electronics, internal scalers and components used, and sometimes manufacturer even provide modes designed to reduce the input lag experienced by bypassing some of these.

There are various ways in which input lag is measured. These are discussed in a lot of detail here at TFTCentral but a common method is using a stopwatch program and recording the images shown on a CRT and TFT in cloned mode using a high shutter speed camera. There are varying levels of accuracy with the different methods used, although the SMTT 2.0 tool is about the best option available without spending hundreds of thousands of pounds on expensive equipment or dismantling your screen completely!

In practice, input lag is unlikely to affect every user. There is quite a lot of fuss made about it on forums, but in reality I would doubt many people will see any real issues on the majority of displays. Some professional gamers who rely on being able to match their key presses and mouse movements with what is shown on the screen might suffer in some cases, so it is something to be wary of. Generally though, I would avoid worrying too much about this issue for most average users. You can classify input lag into three categories as well based on the measured lag:

  • Class 1) - Less than 16ms / 1 frame lag - should be fine for gamers, even at high levels
  • Class 2) - A lag of 16 - 32ms / One to two frames - moderate lag but should be fine for many gamers. Caution advised for serious gaming and FPS
  • Class 3) - A lag of more than 32ms / more than 2 frames - Some noticeable lag in daily usage, not suitable for high end gaming

< See the TFT Central Input Lag Article for more information >


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Dynamic Contrast

Several manufacturers have introduced dynamic contrast controls to their monitors which are designed to improve black and white levels and contrast of the display on the fly, in certain conditions. It is supposed to help colours look more vivid and bright, text look sharper and enhance the extremes ends of the colour scale, making blacks deeper and whites brighter. This is achieved by adjusting the brightness of the backlighting rather than any adjustments at the matrix / panel level. The backlighting can be made less intensive in dark scenes, to make them even darker, and more intensive, up to the maximum, in bright scenes, to make them even brighter.

The official numbers for dynamic contrast are arrived at in the following manner: the level of white is measured at the maximum of backlight brightness and the level of black is measured at its minimum. So if the matrix has a specified contrast ratio of 1000:1 and the monitor’s electronics can automatically change the intensity of backlight brightness by 300%, the resulting dynamic contrast is 3000:1. Of course, the screen contrast – the ratio of white to black – is never higher than the monitor’s static specified contrast ratio at any given moment, but the level of black is not important for the eye in bright scenes and vice versa. That’s why the automatic brightness adjustment in movies is indeed helpful and creates an impression of a monitor with a greatly enhanced dynamic range.

The downside is that the brightness of the whole screen is changed at once. In scenes that contain both light and dark objects in equal measure, the monitor will just select some average brightness. Dynamic contrast doesn’t work well on dark scenes with a few small, but very bright objects (like a night street with lamp-posts) – the background is dark, and the monitor will lower brightness to a minimum, dimming the bright objects as a consequence. Ideally this kind of enhancement shouldn't be used in office work since it can prove distracting or problematic for colour work. However, movies and sometimes gaming can offer some impressive improvements thanks to such technologies.

Dynamic Contrast Ratios are also down to personal taste, as some people like to use them for movies and games, while others do not. Do not be fooled either by crazy manufacturer specs for DCR as they are massively exaggerated and often bear no relevance to what can be achieved in normal use.



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Colour Depth

The colour depth of a TFT monitor is related to how many colours it can produce and should not be confused with colour space (gamut). The more colours available, the better the colour range can potentially be. Colour reproduction is also different however as this related to how reliably produced the colours are compared with those desired.
Some common terms used:

  • 6-bit = 18-bit = 262,144 colours
  • 6-bit + FRC = 16.2 to 16.7 million colours through Frame Rate Control (FRC)
  • 8-bit = 24-bit = 16.7 million colours (true 8-bit)
  • 8-bit + FRC = “30-bit” = 1.07 billion colours through FRC
  • 10-bit = 30-bit = 1.07 billion colours (true 10-bit)

The colour depth of a panel is determined really by the number of possible orientations of each sub pixel (red, blue and green). These different orientations basically determine the different shade of grey (or colours when filtered in the specific way via RGB sub pixels) and the more "steps" between each shade, the more possible colours the panel can display.

At the lower end, TN Film panels are quite economical, and their sub pixels only have 64 possible orientations each, giving rise to a true colour depth of only 262,144 (i.e. 64 steps on each RGB = 64 x 64 x 64 = 18). This is also referred to commonly s 18-bit colour (i.e. 6 bits per RGB sub pixel = 6 + 6 + 6) This colour depth is pretty limited and so in order to reach 16 million colours and above, panel manufacturers commonly use two technologies: Dithering and Frame Rate Control (FRC). These terms are often interchanged, but strictly can mean different things. These technologies simulate other colours allowing the colour depth to improve to typically 16.2 million colours.

  • Spaital Dithering - The dithering method involves assigning appropriate color values from the available color palette to close-by pixels in such a way that it gives the impression of a new color tone which otherwise could not have been created at all. In doing so, there complex mappings according to which the ground colors are mutually assigned, otherwise it could result in color noise / dithering noise. Dithering can be used to allow 6-Bit panels, like TN Film, to show 16.2 million perceived colours. This can however sometimes be detectable to the user, and can result in chessboard like patterns being visible in some cases.
  • Frame Rate Control / Temporal Dithering - The other method is Frame-Rate-Control (FRC), also referred to sometimes as temporal dithering. This works by combining four colour frames as a sequence in time, resulting in perceived mixture. In basic terms, it involves flashing between two colour tones rapidly to give the impression of a third tone, not normally available in the palette. This allows a total of 16.2 reproducible million colors. Thanks to Frame-Rate-Control, TN panel monitors have come pretty close to matching the colors and image quality of VA or IPS panel technology, but there are a number of FRC algorithms which vary in their effectiveness. Sometimes, a twinkling artefact can be seen, particularly in darker shades, which is a side affect of such technologies. Some TN Film panels are now quoted as being 16.7 million colours, and this is down to new processes allowing these panels to offer a better colour depth compared with older TN panels.

Other panel technologies however can offer more possible pixel orientation and therefore more steps between each shade. VA and IPS panels are traditionally capable of 256 steps for each RGB sub pixel, allowing for a possible 16.7 million colours (true 8-bit, without FRC). These are referred to as 8-bit panels with 24-bit colour (8-bit per sub pixel = 8 + 8 + 8 = 24). While most IPS and VA panels support 8-bit colour, modern e-IPS and AH-IPS panels do sometimes use 6-bit + FRC instead.

10-bit colour depth is typically only used for very high end graphics uses and in professional grade monitors. There are three main ways of implementing 10-bit colour depth support. Most screens which are advertised as having 10-bit support are actually using true 8-bit panels. There is an additional FRC stage added to extend the colour palette. This FRC can be applied either on the panel side (8-bit + FRC panels) or on the monitor LUT/electronics side. Either way, the screen simulates a larger colour depth and does not offer a 'true' 10-bit support. You can also only make use of this 10-bit support if you have a full end-to-end 10-bit workflow, including a supporting software, graphics card and operating system. There are a few 'true' 10-bit panels available but these are prohibitively expensive and rarely used at the moment.



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Pulse Width Modulation (PWM)

Monitor flicker is a topic which has only really popped up within the last couple of years, mostly because of the arrival of LED backlights. As a brief background, for many years the brightness regulation of an LCD monitor has been controlled using a technique called Pulse Width Modulation (PWM). This technique basically turned the backlight on and off rapidly to allow for brightness reductions. As you lower the brightness setting in the OSD menu, the “off” period of the backlight is increased to bring about lower perceived luminance. This cycling can run at varying frequencies depending on the backlight system being used, from low frequencies like 140Hz (140 times per second) up to several thousand Hz.

With the arrival of LED backlights, the on and off flashing of the backlight on PWM-dimmed displays becomes more pronounced as the LED’s can turn off and on more quickly than older CCFL backlights. This affects a lot of users who can suffer from eye fatigue, headaches, eye strain etc (and sometimes even visible flicker) especially where frequencies are lower. As a result a lot of people try to avoid screens with PWM backlight dimming.

Some manufacturers are now actively providing flicker free displays, using a backlight dimming technique called Direct Current (DC) where PWM is no longer needed. This eliminated eye strain and other issues associated with PWM. Look out for monitors specifically advertised as flicker free if you are worried at all about this, or have suffered on other screens before. Some screens are not advertised as being flicker free, but may be found to be PWM-free from reviews.

See here for an up to date list of flicker free monitors.


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Blur Reduction

One area which cannot be eliminated fully through response time improvements is perceived motion blur. This is related to how the human eye tracks movement on hold-type displays like LCD’s. In recent years several methods have been used to help provide improved motion blur for users. Models featuring LightBoost backlights for 3D gaming were found to be “hackable” to bring about motion blur benefits through the use of their strobed backlight system. Other displays have now introduced native strobed backlights to offer similar benefits. Look out for models with Motion Blur Reduction backlights like the BenQ XL2420Z / XL2720Z (Blur Reduction mod), Eizo Foris FG2421 (Turbo 240) and Asus ROG Swift PG278Q (ULMB) for instance.
 
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Man of Honour
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thanks mate :) thought it was about time for an update....i might extend the input lag graph a bit further as well.

any suggestions from anyone about what to include are welcome :)
 
Soldato
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Excellent work, really useful. Thinking about getting a new screen myself soon so i've bookmarked this.

You don't happen to know off the top of your head which is THE LCD to get at the moment, 22" upwards? :)
 
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well i dont think there is a single TFT for everyone, it really depends on your needs, budget, features you want etc? Let me know and i can def give you some advice :)
 
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£400 budget, used for gaming on xbox and for PC. Currently have a 26" Sammy, which is a great LCD but i want something with a higher resolution. If any have component AND VGA that would be useful as it'd save me having to buy the 360 VGA cable. But priority is PC performance etc.

I would like to have a nice looking screen too, some of them aren't spectacular..some are. Don't worry too much about that as what one person deems as nice looking, the other might not! :)

Thank you!
 
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I don't often venture into this part of the forums so forgive me if this is obvious to everyone or if it has been done already but would it make sense to list the various maximum resolutions for TFTs? e.g. 17" = 1280x1024 or 17" widescreen = 1440x900 etc?

Otherwise very comprehensive. :)
 
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I don't often venture into this part of the forums so forgive me if this is obvious to everyone or if it has been done already but would it make sense to list the various maximum resolutions for TFTs? e.g. 17" = 1280x1024 or 17" widescreen = 1440x900 etc?

Otherwise very comprehensive. :)
yep will do :)
 
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£400 budget, used for gaming on xbox and for PC. Currently have a 26" Sammy, which is a great LCD but i want something with a higher resolution. If any have component AND VGA that would be useful as it'd save me having to buy the 360 VGA cable. But priority is PC performance etc.

I would like to have a nice looking screen too, some of them aren't spectacular..some are. Don't worry too much about that as what one person deems as nice looking, the other might not! :)

Thank you!


Well the Dell 2407WFP would fit the bill just about at £411. 24" in size, has component interface as well as many others (inc DVI and VGA). Good S-PVA panel technology, excellent all round performance. A very popular and well established screen, brilliant price too :)
 
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Nice one m8, Only just looking at going over from CRT to TFT this Xmas and this guide has explained a lot to me, in nice easy to understand sections.

Cheers.
 
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It is not really unusual for the manufacturers to talk differential. The monit input response time is a signal relay system which gets passed from pillar to post. You may have a piece of Profile software which manages colour output for instance this may add a 1msec response time to the display statistics.
I, for instance, have just purchased a Samsung 2232BW for my HD work and Photography. Just installed as a Plug and play monitors the response times are lacklustre but using the latest driver software for the panel increased the image parralell between accelleration and I/O. Adding to that a full ICC calibration profile the response times become a flux and even though the above figures should only serve as a guideline remember that you are the one whom altimately has to make the choice.
Read as much literature as possible about the kind of thing you are looking in a monitor and make that a basis for your choice and not another set of figures. Remember the above figure are guidelines and a basic testbed.
I could have the latest fastest and awe inspiring DVD writer but if it doesn't write to a medium that is available to the rest of the public or professional arena that doesn't make it the best. After all If you cannot buy the media for it what is its overall value? Zero.
Which brings me to my next point everything involved in electronics these days is volatile and operates at a Digital frequency. Yor CPU's Digital frequency changes with heat and humidity and the current running through it, combined with the load that is currently placed upon it. This may slow down your PC or even accelerate it. The Monitor is the same First it has to receive a signal from your PC, via the graphics card. The graphics card is the important ingrediant here. What is the signal response of the graphics card? Everything we read these days is how fast that is etc. The monitor may have the response time you really want but is yours graphics card and drivers trully going to give you that. You can run all the tests you want but you are not scientifically going to be able to give real figures without specs on the items used, environment they are being used in and the type of temperature regulation being used along with PC and Graphics card as well. Does the graphics card decrease the monitor's response time and range of output?
These are all valid questions and I would welcome a valid response and not one of: "who the hell does this guy think he is?" It is no good forming conclusions without all the evidence. You cannot convict a person just because the Police say he's guilty. If we believed our own press we would have convicted and killed more people than any army would have.
 
Soldato
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Hi Baddass,

First off great article, explains a lot about LCDs to the average user. The trouble I'm now having is weighing up all the pros and cons to come up with an answer of what to get myself .Okay so here’s my info and I’m hoping you’ll be able to advise me.

BUDGET
Ideally around the £300 mark although I could be persuaded to go to £500 if the extra features are worth it.

SIZE
24” and above (widescreen)

USE
This will be a gaming monitor. I will be playing a lot of Pro Evo, Tiger Woods and FPS games like COD4 and BF2 therefore response times are a must.


The panel type is what is also causing me the most confusion as I had my heart set on a PVA panel (bought into the hype I guess) but reading what you’ve said makes me wonder if I should go for a TN and get more more for my money and a better screen for gaming?

Viewing angles aren’t a major factor for me, so long as physical multiplayer gaming sessions aren’t affected. In other words, a mate or two and I should be able to sit at a slight angle with no distortion.

I would rather have a ghost free gaming monitor than one designed for movies with viewing angles/colour reproduction as I have a TV for that.

I guess in summary, what is the best 24” (or above) widescreen for gaming at £500 or less?
 
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