TFT/CRT Brief I’ll primarily be focusing TFT displays but there is a few mentions of CRT displays. Basically this is to just explain a few of the main points to buying a monitor. The There are a number of questions asked about TFT/LCD screens, and I will try my best to explain them. The most common are below: With monitors, when measuring the size of the screen, there are some things to look for. For instance a 17" CRT monitor only has 15.5" visible. With TFT monitors, a 17" monitor has 17" viewable. Therefor a 15" TFT monitor is equivalent to a 17" CRT and a 17" TFT = 19" CRT etc and so on. TFT displays are usually designed to run at a specific resolution (native resolution). Most 15" TFT displays are designed to run at 1024x768 @ 75Hz. 17” TFT’s run at 1280x1024 @ 75Hz and so on. Although you can use smaller displays like 800x600 but the fonts can look out of proportion and pixelated. Before purchasing it is worth checking that you are happy with this resolution. Advantages of TFT displays: 1.There is much less glare from a TFT monitor. 2.The monitor is far less bulky. This has a couple of advantages, firstly it gives you more desk space, but secondly because of this you can position the monitor further away from you which most people find more comfortable on the eyes. 3.TFT monitors produce less heat and radiation that CRT monitors. 4.TFT monitors have a very crisp image only comparable to very expensive CRT monitors. 5.The monitor (so long as it is VESA compliant) can be mounted on an arm or on the wall to save even more desk space. Disadvantages of TFT displays: 1.If you are working with graphics, although the graphics are very clear, due to the limited angle at which you can view the display colours may appear slightly different on non-TFT screens. 2.TFT monitors have a limited angle of view. This is the angle at which you can clearly view the screen. If you are looking directly at the screen while working on your PC this is fine, but if others are trying to read it then they may have difficulty (try looking at a laptop screen from a 45 degree angle). 3.You may experience some blurring on lower end models when there is movement on the screen. This is most prominent in full screen games where you get a motion blur effect but is also noticeable when scrolling through documents or websites. CRT advantages 1.Accurate color: CRTs can provide richer color in a fuller spectrum than most LCDs. In general, graphic artists prefer CRT monitors because they show truer colors and greater nuance-particularly useful for preparing files for printing and for using photo applications such as Adobe® Photoshop®. 2.Response time: CRTs may respond more quickly than some LCDs to videos and fast-action games. For some LCDs, pixels respond to voltage (being turned "on" and "off") more slowly than the time it takes for an electron beam to redraw a CRT screen. As a result, fast-moving images can sometimes leave visible trails, called ghosting, or appear blurry on an LCD. ViewSonic ClearMotionTM LCDs have virtually eliminated response-time issues. 3.Viewing angle: CRT monitors display good brightness and color from a wide viewing angle. Some LCDs, however, look their best when you are directly in front of them, because of the way light passes through liquid crystals in the screen. Keep in mind that LCD technology is rapidly developing, increasing LCD viewing angels, so this CRT advantage doesn't hold true in every case. Check the specs of the monitors you're considering. ViewSonic XtremeView® LCDs have superior viewing angles. 4.Multiple resolutions: CRT monitors can switch between multiple resolution settings without a significant loss in sharpness. If you need to change your monitor resolution frequently, you may be better off with CRT technology. 5.Lower purchase price: CRT monitors are generally less expensive at initial purchase than LCDs. CRT Disadvantages: 1. Sharpness: The CRT's Gaussian beam profile produces images with softer edges that are not as sharp as an LCD at its native resolution. Imperfect focus and color registration also reduce sharpness. Generally sharper than LCDs at other than native resolutions. 2. Interference: All color CRTs produce annoying Moiré patterns. Many monitors include Moiré reduction, which normally doesn't eliminate the Moiré interference patterns entirely. 3. Geometric Distortion: Subject to geometric distortion and screen regulation problems. Also affected by magnetic fields from other equipment including other CRTs. 4. Brightness: Relatively bright but not as bright as LCDs. Not suitable for very brightly lit environments. 5. Screen Shape: Some CRTs have a rounded spherical or cylindrical shape screen. Newer CRTs are flat. 6. Emissions: CRTs give off electric, magnetic and electromagnetic fields. There is considerable controversy as to whether any of these pose a health hazard, particularly magnetic fields. The most authoritative scientific studies conclude that they are not harmful but some people remain unconvinced. 7. Physical: They are large, heavy, and bulky. They consume a lot of electricity and produce a lot of heat. Refresh Rate Improvements in both CRT design and in driver software should by now have killed off the problem of screen flicker, that goes for TFT’s too. If your screen is flickering as you read this, either the hardware needs replacing or it set to too low a refresh rate. Don't put up with flicker - it will give you headaches, make your work harder to do and possibly cause permanent damage to your eyes. For Windows systems, the refresh rate can be found by clicking on the Desktop and selecting 'Properties' and the 'Settings' Tab. The refresh rate is normally found by using the 'Advanced' button and selecting 'Monitor'. You should only change this after consulting the monitor manual and determining the appropriate values for the screen resolution and number of colours you are using - or again you could damage your monitor or lose the screen display. Tube Designs Looking at CRT monitors, you have a choice of tube designs, including the older 'slot mask' types and the 'aperture grill' present in Sony 'Trinitron' and the 'Diamondtron' from Mitsubishi. The aperture grill types give a sharper image, but you can see two faint lines across the screen from the supporting wires at roughly one quarter and three quarters of the screen height. Some people find these impossibly intrusive, but I soon grew to ignore them. The better picture quality more than made up for the slight inconvenience. For most people, a refresh rate of 70Hz or greater will get rid of any flicker, although occasionally some experiment is needed, as certain combinations of values may give problems. You may also want to change the size of your screen fonts. You may also get information about your monitor from any on-screen monitor menus. Resolution Size for size, because of their finer dot pitch, CRT displays can use higher resolutions than TFT screens - perhaps 1880x1440 or more for a 21-inch screen. CRTs are also 'multi-synch', giving you a wide choice of resolutions and colour depths to run at. TFT screens are designed to be used at their actual physical resolution and although most can be set to work at other sizes, the picture quality suffers, often dramatically. If you have an 1024x768, screen you need to use it at that size, for the visual side and for the life of the screen. Bit Depth Not all TFT screens that claimed to work in 24 bit colour actually did so. Many were made that work with only 6 bits per sub-pixel, giving only 64 possible shades of each colour. The remaining two bits of each 8 were simply ignored. This become even more of a problem if you want to work on black and white images, where 64 grey shades is usually clearly insufficient.
Colour All except the cheapest CRT screens give more or less consistent colour for any particular signal value across the whole screen (they use the same phosphor across it.) With TFT there is often some variation and colour across the screen is less accurate. Testing of most TFT screens with colour calibration hardware also shows them to be generally inferior to CRT displays in giving accurate colour. The best TFT screens designed for imaging work will give good results, but cheaper models are generally less reliable. However they are suitable for less critical work. Increasingly the hardware solutions for monitor calibration are produced so they will also work with TFT displays, but they may not work as well, or may take more care in use. You need to be much more careful with the surface of the screen than with the protective glass over a CRT monitor. TFT displays also vary quite widely in the contrast range they support. The better models give a range of perhaps 4-500:1. Viewing Angle Although many TFT displays are now very bright when viewed head on, most still fall off fairly dramatically when you move your head to one side,similar to a rear projection TV, and colours may change. This can be annoying when you want to compare images on two screens for example, or when you want to discuss an image with several people - they can't all be in the best viewing position. Although some more recent screens are much better than older models, CRT displays are still generally better when viewed from the side, especially if you have a Flat Screen. Size, Weight and Cost etc TFT displays do have the obvious advantage in size and weight, and perhaps less obviously in lower power consumption. However for the cost of a cheap TFT display you can buy a good CRT that will be much more suitable for working with images, and allow a much higher resolution when required. TFT displays marketed especially for imaging professionals are still expensive - perhaps thousands rather than hundreds of dollars. If you are looking at a second display for your system, one of the cheaper TFT screens might be a good choice, especially if you want to make use of the portrait format display option some offer. It is vital of course to check the specifications carefully to make sure exactly what it offers; in particular you need to check the actual device resolution, the brightness and the contrast ratio. If you have a TFT display, even some of the less adequate ones built into some notebooks, don't be too despondent. You can still get good results from your images, even if you will not be able to have quite the same control over your work. What To Look For When Buying Response Times are the primary concern of any TFT LCD screen. Viewsonic is advertising their VP201s monitors as having Response Times that are fast enough to present "Realistic, artifact-free 3-D gaming. These monitors have a "16 millisecond Response time. Hitachi also advertises their CML174B and CML 175B LCD monitors with Response Times of 16ms "enabling smoother computer video, animation and gaming movement." Samsung goes one step better with their 172X LCD monitor that sports an amazing 12ms Response Time. Newer models have gone just another step further with 8 and 6ms response times. Generally for gaming, a response time less than 12ms is respectable and won’t produce any really noticeable ‘blur or ghosting’ in fast paced games. If it’s going to be used for office applications such as Word or Excel, than anything under 20ms will do fine. Next, be sure to select a screen that has a native resolution that meets your needs. That is to say, if your system can only play games at 800x600 then buying a 2048x1536 monster display won’t give you any advantage and will almost certainly do more to hinder your game playing and your enjoyment of it. Check the dot pitch measurement and make sure you are comparing like-for-like if you are looking at more than one display, especially from different manufacturers. High contrast and high brightness, but low power comsuption is a very good combination because this will give you impressive visuals and your display will hopefully last longer. Other, smaller, concerns (like the price) I is purely personal preference. A TFT LCD that satisfies all of these criteria will hopefully do justice to your game visuals and give you the gaming experience that you desire. Final Words The best way to know if a monitor is right for you is to view it in person. Specs are a great tool for narrowing down your choices, but they are no replacement for hands-on experience. Plenty of large resellers stock a wide range of monitors and some are on display. Go down to every shop you can and see if you can find the monitor you are thinking of buying. You never know, that slightly low spec one you shunned in favour of that extra inch of screen may beat everything else hands down in ‘real world’ performance.
