Monitors the Buyers Guide

In this guide we'll talk you through some of the commonly encountered buzzwords and specifications. After just a few minutes you'll be much better prepared to start the buying process.

TFT versus CRT
Cathode-ray tube monitors seem to have gone out of fashion recently, mainly due to the rapidly dropping prices of sexy-looking TFT (thin-film transistor) flat-panel models. But remember that CRT technology is well over 100 years old and still has a lot of strengths.

CRTs are bulky, heavy and consume a lot more power than TFTs, but a canny buyer would do well not to dismiss CRTs out of hand given their excellent value for money.

Resolution
Resolution refers to the number of graphics elements displayed on a screen. These elements are known as pixels and are generated by your graphics card.

In any monitor, TFT or LCD, each pixel is composed of three sub-pixels coloured red, green and blue. In a CRT monitor these pixels (each composed of three phosphor dots) are spread in a grid across the screen separated by a distance called the dot pitch. The smaller the dot pitch, the sharper the screen will look at a given resolution.

With TFT panels, each pixel is composed of three rectangular thin-film transistors. The number of pixels equals the 'native' resolution: a 1,024 x 768 TFT will have exactly that number of pixels horizontally and vertically.

CRTs usually have a higher resolution than a TFT of the same size, and work perfectly at any standard resolution up to the quoted maximum. Running a TFT below its native resolution (the number of pixels in the TFT) can result in either a very poor 'blocky' picture, or one that doesn't fill the whole screen.

THE STALWARTS: CRTs

Let's start with what to look for in a CRT monitor. The majority of CRTs these days are flat-screen models, which are much more pleasant to use than the old curved-screen models.

Size
Most users will be happy with a 17in or 19in CRT. Larger sizes tend to be very heavy but they are popular for graphics-intensive work such as desktop publishing or photo editing.

Menu controls
Good CRTs have a wide range of menu-driven adjustments that let you compensate for inevitable distortions in the display. Make sure there are at least menu controls to adjust for brightness, contrast, horizontal and vertical position and size, pincushion, trapezoid, parallelogram, convergence and colour balance.

Ergonomics and standards
Ensure there's a smoothly operating tilt-and-swivel base fitted. A CRT should support at least an 85Hz refresh rate for any resolution you use to avoid flicker in the image. Cheap models might not achieve this at their maximum resolution. Check the data sheets closely.

One of the most important standards for CRTs is the TCO label. This guarantees compliance with stringent electromagnetic emissions, ergonomics, energy saving and environmental requirements. For more information and a searchable database of compliant models have a look here.

The latest standard is TCO-03, but you may also see older standards such as TCO-92, 95 or 99. Avoid monitors with no TCO labelling.

THIN IS IN: TFTs

Everyone seems to want a TFT monitor, because they're stylish, compact, easy to move around and very affordable. But there's a lot of misinformation around and you need to check the specifications a little more closely than you do with a CRT.

Resolution
First, check that the native resolution is sufficient for your needs - for example, gamers wanting to run 1,600 x 1,200 will probably need an expensive 20in model - 19in panels are currently limited to 1,280 x 1,024, and budget 14/15in models might only support 800 x 600.

Viewing angles
Modern TFTs can be viewed from a wide range of angles vertically and horizontally, but anything over +/- 45 degrees doesn't really make any difference in normal use. Don't write off a monitor for the sake of a few degrees difference in quoted viewing angle.

Response time
Another buzzword to take with a pinch of salt: response time is the time taken for a pixel to reach maximum brightness, but there's no agreed standard for measuring it.

In the old days, TFTs had response times of 125ms or more and were poor at displaying moving graphics such as a cursor. Nowadays 12-25ms is standard and you won't notice any substantial difference within that range.

Contrast and brightness
TFTs have high quoted contrast ratios, but this is often a maximum figure so don't take it as gospel. If you regularly work in a very bright room, see if you can get a home trial before committing to a purchase, or look for vendors with a money-back refund policy.

Evenness of lighting is more important than the overall brightness specification, but you can only tell this from looking at the monitor.

Adjustments
Early TFTs were very difficult to set up, but most new TFTs have an auto-calibration function. Some are better than others, so make sure there are manual adjustments available as well.

A poorly adjusted TFT will have a 'squirming' or misaligned display. If your graphics card has a digital (DVI) ouptut, choose a monitor with a DVI input as you then won't need to make any manual adjustments.

ISO and TCO standards
The ISO 13406-2 standard specifies minimum requirements for display contrast, viewing angle, brightness, reflections, flicker, contrast and defective pixels. You may see the standard incorporated in a TUV label with the words 'Ergonomics Approved' or 'ISO 13406-certified'.

The TCO-95 and TCO-03 standards cover electromagnetic emissions, noise (yes, bad TFTs can be noisy) and ergonomics. You should ensure that your monitor has at least one of these certifications. Check at www.tcodevelopment.com.

ISO 13406-2 has stringent standards for defective pixels, related to the resolution of the screen and the type of defect. Only Class I TFTs are guaranteed no defective pixels. Most consumer models are Class II.