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TFT Info and Mini-Reviews

Discussion in 'GH Archive' started by arty, 24 Oct 2002.

  1. arty

    Soldato

    Joined: 18 Oct 2002

    Posts: 6,663

    Location: Cambridge

    This is a re-post of the original sticky I wrote a few months ago :) Thanks to Werewolf for saving it and e-mailing it to me so I could post it again. It's a bit out of date as of now (24/10/2002) but I might update it in the near future, if I have time.

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    As there seems to be an awful lot of interest in TFT / LCD / flat-panel monitors in GH at the moment, I thought it might be useful to have one big sticky full of information and also a link to a table of OcUK forum users' reviews of their monitors (taken from this thread which A[L]C had the great idea of starting).

    This thread is concerned with desktop TFT monitors (as I shall call them from now on), the screens which they use having first appeared in laptops. In the last few years, the price of desktop TFT monitors has dropped enough to make them a fairly viable (although still expensive compared to CRT monitors) display option for many users, as well as a continually improving quality.


    Sizes

    The most obvious difference between a TFT monitor and a CRT monitor is size - TFT monitors are MUCH thinner front-to-back than CRT monitors, as this image illustrates (my new Eizo L365K 15" TFT monitor compared to my old CTX PR711F 17" CRT monitor) :

    [​IMG]

    Obviously, the TFT monitor wins hands down in terms of footprint. The casing required to house the TFT screen itself is also considerably smaller than with the CRT, so there is much less of a border around the screen than with a CRT monitor.


    Resolutions and Screens

    As TFT screens consist of a finite number of individual pixels, they MUST be run at the fixed resolution which they are made to provide the sharpest image. For instance, 15" TFT monitors are usually made at a fixed resolution of 1024x768 pixels. There is absolutely no way you can display a higher resolution than this on such a TFT monitor, and usually there is a fairly small range of smaller resolutions which are supported (640x480 and 800x600 being the standard ones). Of course, as neither of these can be multiplied up to give the native 1024x768 resolution of the screen (unlike 512x384 in this case), some anti-aliasing must occur in order to render a resolution which the screen cannot normally display - so these lower resolutions will appear with quite a blurred picture. It is VITAL to run a TFT monitor at it's native resolution, or the benefit of the perfect geometry and pin-sharpness of a pixellated screen is wasted.

    The screen area of a 15" TFT monitor is roughly comparable to a 16.5" CRT monitor - this is because the whole of the screen is visible in TFT monitors, whereas in CRT monitors the tube must be built into the frame around the screen, therefore reducing the viewable image size. As already mentioned, 15" TFT monitors usually have a fixed resolution of 1024x768, and 17" / 18" monitors tend to be 1280x1024 (although in the more expensive cases you can find 1600x1200 screens). Bearing in mind that a 15" TFT monitor is usually compared directly to a 17" CRT, most good CRT monitors can display up to 1600x1200 fairly well, and certainly up to 1280x1024 with a fairly sharp picture at high refresh rate.

    So, then, if you're a CRT monitor user who uses a high (1280x1024 or greater) resolution, you might find it difficult to adjust to the considerably smaller resolution of most of 15" TFT monitors.


    Colour Intensity, Contrast and Brightness

    The quality of TFT screens has come on leaps and bounds in the last year or so, such that the best models nowadays are finally realistically comparable to mid- to high-end CRT monitors in terms of picture quality. Although TFT monitors tend to be excellent at displaying midtones and brighter shades of colours, the darker hues often suffer in comparison to CRT monitors. My Eizo L365K, which has a contrast ratio of 450:1 (about the second-highest out there for a TFT monitor), has difficulty displaying a true black shade, whereas most CRT monitors can easily cope with very dark images - this is particularly noticable when watching DVDs or playing dark games, where the colour range tends to be greater than in Windows. The very lightest shades can sometimes also cause problems for TFTs, although this is less of a problem nowadays than it used to be.

    If the accuracy of displaying colours must be high for you, the very highest-range TFT monitors are really the only ones that come close to high-range professional CRT monitors, and even then they are not quite yet good enough for essential colour-matching work (e.g. in DTP or photo-editing).

    TFT monitors tend to excel at image brightness - my Eizo is so bright that it actually casts a discernable image onto the wall behind me in the dark! Admittedly this is an exceptional example (it has an unusually high brightness rating of 350cd/m²), although all TFT monitors tend to be considerably brighter than their CRT counterparts.


    Response Times

    For gamers, the biggest issue with monitors of any sort tends to be the frequency at which the image refreshes. On CRT monitors, refresh rates as high as 160hz are fairly common, and higher-end gamers (particularly in FPS games such as Q3 and CS) tend to use refresh rates of 100hz or higher. This means that the moving image displayed on their monitor will change 100 times a second - and if used in conjunction with v_sync, the game will run at 100fps without any tearing (assuming the rest of the computer system is up to running it at that speed constantly).

    TFT monitors are different in this respect. Because there is no electron gun to scan through the screen, every pixel refreshes independently - so there is no overall 'refresh rate' as with CRT monitors. Instead, TFT screens measure the average 'response time' of each pixel - the time it takes for a single pixel to change colour. Typical values of TFT monitor response times are around 25-50ms - bear in mind that in online FPS gaming, a ping greater than around 20ms starts to become noticable (at least to me). You can come up with a rough estimate of refresh time from this - my Eizo TFT monitor has a response time quoted at 25ms. To convert that into hz, you can use this simple formula:

    1000 / response time = refresh rate (estimated)

    So my Eizo TFT has a refresh rate of around 1000 / 25 = 40hz or so. Notice that this is MUCH lower than the 100+hz I quoted as being optimal for most high-end FPS gamers. In practice, the moving image tends to blur VERY noticably in Q3 (the game I play to a fairly high standard), although it's important to bear in mind that:

    1. I've got used to it (after a week or so of fairly intense playing)
    2. I run on 'l33t' graphics which are very low-contrast, making movement slightly harder to follow
    3. I have quite a twitchy playing style (I move around fairly quickly)
    4. I was used to playing at 120hz

    To me, the benefits of having a very light, thin, small TFT monitor over a heavy, deep, huge CRT vastly out-weigh the blurry effect, which as I've said I have now become totally used to. However, gamers are notoriously picky folk, so if you'd class yourself as a 'hardcore' gamer, I would say that it is ABSOLUTELY VITAL that you try playing on a TFT before buying one, or you might end up with a monitor that you find your game to be totally unplayable on. At the end of the day, it's very much down to personal preference, although some TFTs are better than others for games - if you play a lot of games (and also watch DVDs, although as they usually only run at 25fps this is less important), try to aim for a TFT monitor with as low a response time as possible. 30ms and below is good.
     
  2. arty

    Soldato

    Joined: 18 Oct 2002

    Posts: 6,663

    Location: Cambridge

    [continued]

    Sharpness, DVI and Dead Pixels

    As TFT screens have discrete individual pixels, they are by far the sharpest native displays you can get at the moment. However, if you connect a TFT monitor using an analogue connection, there's no guarantee that you will get a 'perfect' image, as the TFT monitor will have to convert the analogue signal into digital form. This could well introduce slight artifacts if the graphics card producing the analogue RGB output doesn't quite have a high-enough quality output, or the converters in the TFT monitor aren't quite up to scratch.

    To get round this, many TFT monitors are starting to include DVI sockets. DVI is a relatively new digital video standard which will effectively eliminate the conversion from Digital -> Analogue -> Digital which will occur if you connect a TFT monitor using a traditional analogue RGB connection.

    There are two variations on the connectors used in the DVI standard - DVI-D and DVI-I. DVI-D is designed for use exclusively with TFT monitors, whereas DVI-I sockets also contain 5 analogue pings which can be used with a suitable cable to connect a standard CRT monitor.

    Although the difference in image quality between DVI and analogue RGB connections with TFT monitors is fairly small, DVI will always provide the best quality image as there is no conversion from the graphics card to the screen. If you want to use a DVI connection, it's important that you check to see exactly which socket is on the graphics card you wish to use with the TFT monitor, and also to bear in mind that in the overwhelming majority of cases, TFT monitors do NOT come with DVI cables - you have to buy them seperately. This is not cheap - the cable I bought with my Eizo monitor cost around £50 from a well-known retailer, although various auction sites have been known to have auctions of DVI cables for much, much less than this.

    Sometimes, a pixel may 'get stuck' on a TFT monitor. This can manifest itself in one of several ways - a pixel that is overly tinted or stuck at red / blue / green (when only one of the colour elements is faulty), or a pixel that is stuck at black or white (when all three elements are faulty). Due mainly to the high cost of manufacturing TFT screens, not all manufacturers (particularly in the cheaper models) will replace a TFT monitor in the case of dead pixels. Some common numbers :

    - Up to 7 dark dead pixels are allowed before a replacement is necessary
    - No light dead pixels are allowed

    ...although these vary from manufacturer to manufacturer - it is usually a good idea to check with the makers of each TFT monitor that you are considering to find out exactly how many dead pixels are required before they will replace the monitor.


    Viewing Angles

    One of the biggest differences between TFT monitors and their traditional CRT relations is the viewable angle of the screens. With a CRT monitor, you can look at the screen from any angle without any real change of colour or brightness. However, due to the LCD-like nature of TFT screens, the image that you see varies depending on the angle and position at which you are looking at the screen, as this photo attempts to show (the fish-eye distortion on the first picture is due to my camera, not my screen) :

    [​IMG]

    As the optical effect that the viewing angle causes is hard to capture on camera, you really need to see a TFT screen in real life before fully understanding exactly what it looks like.

    Basically, smaller TFT monitors are not brilliant for group viewing, although if (as in most cases) the screen only really needs to be seen by one person at a time, the viewing angles tend not to be so much of a problem as long as you position the TFT monitor correctly.


    Price

    The cheapest new 15" TFT monitors I've seen have been £200, as stock clearance, and these are usually several months at least out of date compared to the newest models. Average price ranges (including VAT) are:

    - £250-£500 for a 15" TFT (1024x768)
    - £450-£1000 for a 17" TFT (1280x1024)
    - £500-£1400 for an 18" TFT (1280x1024)
    - £1600-£2000 for a 17" / 18" TFT (1600x1200)

    Clearly only the 15" TFTs and the lower-range 17" TFTs are currently at comparable prices to expensive CRT monitors, mostly due to the high-cost and low-yield of the TFT screen manufacturing process. Prices may drop, but it's unlikely, without the introduction of new display technology, that they will drop all that much in the forseeable future.


    OcUK User Reviews

    (Thanks to A[L]C for starting the pre-nuke thread which these reviews are taken from)

    Here is a large table exported from Excel which contains mini-reviews of TFT monitors that OcUK forum members own or have used. It includes basic specifications (where I've been able to find one) in addition to the opinions and prices that the OcUK forum users posted in the original thread, and also links (again, where I've found them) to the monitors in question.

    I'm happy to continuously update and add to this table if people want to email me with mini-reviews or opinions, preferably stating :

    - Manufacturer
    - Model
    - Good / Bad points
    - Price paid (optional)
    - URL to monitor (optional, but helpful)
    - A rough score out of 10
    - Your OcUK forum user name

    Hopefully this table will become an excellent resource for the many people interested in TFT monitors on the OcUK forums.


    Links and Disclaimer

    Some interesting / useful links to those interested in TFT monitors (can also be added to) :

    - TomsHardware 15" TFT monitor round-up (part 1)
    - TomsHardware 15" TFT monitor round-up (part 2)
    - Anandtech article on DVI and image quality
    - Monitor Toolkit (useful for diagnosing simple problems with CRT and TFT monitors

    All of the above is written purely off the top of my head, and as such may contain mistakes. Many of the most hotly-debated issues with TFT monitors are down to personal preference, so please don't flame me complaining about such-and-such a monitor that you bought after comparing the specification to the (fairly rough) explanations in this guide. This sticky is meant purely to help clear up and answer some of the most common TFT threads in GH, and so is not meant to be a be-all and end-all guide, although I am entirely open to suggestions for content to add or explanations on any terms.

    arty
     
  3. Werewolf

    Commissario

    Joined: 17 Oct 2002

    Posts: 28,594

    Location: Panting like a fiend

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