monitor should I choose ?
By Tom Cumming
There are two parts to the formation of a PC's display: the monitor and the graphics card. The two have to be matched carefully, just like you would not select buy tyres without considering what kind of car they will be used on.
There are three items that determine the theoretical quality of the image on a PC's screen:
1) The resolution: A PC's display is split up into a number of tiny little dots, called pixels. The number of pixels your computer uses is called the resolution, and is described by indicating the number of pixels up the side of the screen, followed by the number of pixels across the screen horizontally. So, the higher the resolution, the more you can fit on the screen. If you use too low a resolution, everything will look enormous on the screen, whereas if you use too high a resolution, the screen will be difficult to read. These are the typical "best" resolutions for each monitor size:
2) The colour depth: The number of colours the display can show at a time. High colour (16bit) or True colour (32bit) are the most commonly used depths. Lower depths than this are best avoided, as images will sometimes appear with incorrect colours.
3) The refresh rate: the number of times the display is redrawn per second. The higher the refresh rate, the less flickery the image will appear. However, at very high refresh rates the graphics card is worked hard so sometimes it causes the display to become less sharp. For most systems the tradeoff occurs at about 75-85Hz, unless you have a TFT flat panel monitor, in which case flicker is much less of a problem and the minimum 60Hz is fine.
All of these three items depend on the memory on your computer's graphics card. The more memory your graphics card has, the higher the maximum resolution, colour depth and refresh rate can be. So, before you start chosing a monitor you need to find out how much memory your graphics card has, by looking in your graphics card's handbook or contacting the manufacturers.
If you have a graphics card with 32Mb of memory or more, then this is unlikely to be an issue. However, if you have a graphics card with less memory than this, you need to find out what is the maximum resolution it can display. This is because there would be little point in purchasing a 21" monitor if your PC can only display upto a resolution of 800x600, because a 15" monitor can display an image at 800x600 perfectly adequately (see above), and the only benefit of a 21" monitor over a 15" monitor would be that everything would appear larger. It would not allow you to fit any more onto the screen, so unless you have problems with your eyesight and could do with things being very big, then this would be a waste of money. You will normally find that there will be tradeoff between colour depty, refresh rate and resolution: if are running your graphics card near to its limits, and you decide to increase your resolution, you may have to decrease your colour depth or refresh rate to have enough memory to do this, for example.
Once you've decided on your screen size, according to your graphics card, you are now faced with deciding which type of monitor to go for. Monitors can be grouped into three distinct categories:
1) Shadow-mask CRT monitors: These are the most basic monitors, using a Cathode Ray Tube (CRT) to produce the image, in the same manner as a television. Behind the screen is a metal sheet with holes in (the shadow mask) that directs the light to the correct places (in very simplistic terms!) These are the cheapest monitors but still produce pretty good images. However, even the best, most expensive ones have a noticeably curved surface.
2) Aperture-grill CRT monitors: These are like (1), except that instead of a metal sheet (shadow mask), behind the glass they have a series of metal wires to direct the light. This means that more light actually goes through the glass, and less hits the metal and is reflected back into the monitor. Therefore these monitors produce a much brighter, clearer picture, and can cope with higher resolutions than their shadow-mask counterparts before they become difficult to read. For example, I have a 17" aperture-grill and I am running at 1152x864, whereas for most 17" shadow-mask monitors, the best resolution is 1024x768. These monitors are also flatter than shadow-mask monitors. The first aperture-grill monitors were made by Sony under the Trinitron brand (along with the more famous Trinitron aperture-grill televisions), but they have licenced the technology to a number of other manufacturers such as Mitsubishi, who call them Diamondtrons. Most monitors that are described as "flat-screen" are aperture-grill monitors. They are a fair bit more expensive than a shadow-mask monitor, but personally I would rather get a smaller aperture-grill monitor than a larger shadow-mask monitor, because of the better image quality. The only other minor snag with these monitors is that in order to prevent the metal wires of the aperture grill from shaking when somebody walks past the desk, they have two horizontal damping wires running across the screen at one third and two thirds of the way down, and these are slightly visible on the display as feight dark shadows. Most people do not notice these but others hate this.
3) TFT/LCD flat-panel monitors: These have the obvious advantage of being extremely thin and space saving. They also draw much less power than CRT monitors. The image quality is generally better than CRT monitors in terms of geometry, but not as good in terms of colour, so you need to have a look at a few in operation to see if you like them. Their screen sizes are larger than CRT monitors for their given number of inches, because CRT monitors have part of the CRT covered over by the casing, but this is not the case with LCD monitors. The main drawback with TFT monitors is the price, though having said this the prices are coming down all the time. It is also noticeable with larger LCD screens that the apparent brightness of the screen varies according to the angle at which you look at it. Take a pocket calculator and switch it on. Press some numbers. Now look at the screen from directly above. Now tilt it forwards and backwards and you will notice the screen appears to get brighter or darker. You will get the same effect on an LCD PC monitor, and so it will often look like the top of the screen is darker than the bottom of the screen, which takes a bit of getting used to. Something else to bear in mind is that TFT monitors only have one resolution they are designed for, and all other resolutions will have a poor, fuzzy image quality. For this reason I will not recommend TFT monitors to people who play a lot of games, because a lot of games run at different resolutions that cannot be changed. LCDs are also slightly slower in updating the screen than conventional CRT monitors, so are not ideal for animation and 3D graphics work.
Another important factor to bear in mind is the connector. All CRT monitors for about the last 10 years have used a connector called "D-Sub", which looks like a serial connector with a few more pins. The digital image, made up of pixels, produced by the PC, is converted into an analogue signal by your PC's graphics card (or onboard graphics chip) and fed down the D-Sub lead to your monitor. This was all very well until LCD monitors came along, which required a digital signal. The first LCD monitors were still fitted with a D-Sub cable and an analogue-to-digital converter to get the signal to a digital form. This means that if your PC had an LCD monitor and a D-sub monitor connection, then the digital video signal would be converted to analogue in the graphics card, and then back to analogue again in the monitor! This of course means a slight loss of quality.
So, what happened is the manufacturers introduced a new connector, called DVI, or Digital Video Interconnect (or is it Digital Video Interface? It seems to depend which magazines you read! But anyway....) This connector bypasses the digital-to-analogue converter in your PC's graphics card, and outputs a digital signal directly. If you then connect this to an LCD monitor, which also has a DVI connecotr, you get a better image quality than you would with a D-sub cable and the same PC and monitor. Also, because there is no analogue signal at any point in the transfer, it means that you do not have to adjust your monitor's width, height and size adjusters.
In fact, even a lot of CRT monitors now come with DVI connectors, with the eventual plan being that PC graphics cards will not be fitted with digital-to-analogue conveters any more, and will be built into the CRT monitors instead. Then, if you have an LCD monitor, you will not have to pay money for a digital-to-analogue converter that is never used.
So, my advise would be: check if your graphics card has a DVI connector. If you do not have one, then I would be wary about buying an LCD monitor. Make sure that if you chose to buy one, that the retailer will refund your money after a few days if you are not happy, even if it is not damaged. There is no legal obligation for retailers to do this, but many do anyway out of goodwill. Therefore, if you get your shiny new LCD monitor home and find the picture quality is terrible, you can then take it back and switch it for a CRT monitor. If your graphics card *does* have a DVI connector, then try and get a monitor with a DVI connector if at all possible.
NB: The D-Sub connector has 15 pins, but not all of these are used. Therefore, on some D-Sub leads, some of the pins are not fitted, and the plug will look like some of the pins have broken off. This is not a fault: this is intentional. Do not think you need to buy a new lead!
So, once you've chosen your size, screen type and connector type, you have narrowed down your options quite considerably. I would now start to draw up a shortlist of models that are available within your price range, that fit your size, screen type and connector type requirements. Then go into a shop that has some of your shortlisted models on display, and have a good look at them in operation to see which you prefer. It is really down to good/bad makes, personal preference, price and appearance by now. Some makes I have heard good things about are:
A few other things worth checking:
1) The cable: Check that the monitor cable is completely detachable, and not permenantly connected to the monitor. This way, if the cable gets damaged you can just buy a new cable and not a whole new monitor. Also make sure that the cable is long enough to reach to your system box, obviously.
2) On-screen display: most monitors have their geometry set up by an on-screen menu system. Some of these systems are much easier to use than others, so it is a question of getting recommendations and/or trying a few out in a shop for comparison.
3) Built-in extra toys: Some monitors have built in speakers, microphones and/or USB hubs. If you need any of these items anyway and wish to save space by having them built into the monitor, then go for them. However, if you do not need them then do not buy a monitor that has them, as it is just one more thing to go wrong or cause complications. It also means the money being spent by the manufacturers on these extras is not being spent on the most important thing: the image quality.
4) Depth: Some larger CRT monitors are enormous great things, so measure them to make sure you've got a big enough desk space behind it, as they often look smaller in the shop when sat next to lots of others, than they do on their own at home or in the office. I know that Philips do a special range of "short-neck" monitors if space is a problem.
5) Warrantee: How long will is it guaranteed to work for and what will the manufacturer do about it if it does not live up to the guarantee. I would recommend avoiding smaller brands you have not heard of, so that you have less risk of them going bust and therefore not honouring their warrantees.
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