Choosing the right technology for the big picture

, posted: 13-Feb-2004 22:19

Shopping for a television set is no longer simple. Walk into the TV section of any appliance or department store and you will be greeted with a bewildering array of display technologies - CRT, rear or front projector, LCD or plasma - each of which has its strong points and weaknesses. So, where to begin?

We've taken a look (literally) at the different big-screen types on the market today, and assembled a few tips to make it easier for you.

CRT: the allround big screen, 29in to 40in.
Prices start at below $1000 for 29in; larger and wide-screen models can be over $5000. Ye olde CRT (cathode ray tube) is still the best choice for most people. To start with, the image quality is very good, especially if you pick a 100 Hertz screen (which doubles the normal, and somewhat flickery, 50 Hertz refresh rate of standard TVs).

These offer a very sharp display, with good colour reproduction and fast response rate, albeit at a single resolution. The image is bright enough to be viewed in bright ambient light as well. Further, CRT TV sets almost always come with TV tuners and stereo sound receivers/amplifiers, so you don't need separate boxes to start viewing.

CRTs are good value compared with other technologies, although LCDs (liquid crystal displays) have started to encroach on their territory. The main drawback to CRTs is their size. From 29in and beyond, you're looking at a heavy beast that needs a good chunk of space - the rare 40in screens weigh 90kg.

In reality, it's hard to find CRTs larger than 32in, so if you need bigger than that, go for plasmas or projectors instead. Not all CRTs are flat-screen either, but how much the amount of curvature annoys varies from person to person. Viewing angles are good in all directions, however, making CRTs easier to position - you don't need to be right in front of the screen for best results.

Then there's wide-screen, which as the name implies features a screen wider than it is tall, just like at the
cinema. The two most common aspect ratios are 4:3 and 16:9. Although foreign TV programmes are recorded in wide-screen format, no New Zealand broadcaster currently transmits them as such. DVDs and pre-recorded video can take advantage of wide-screen.

The widescreen format also goes across the following technologies:

Projectors: big but affordable, 72in to 106in and beyond.
Prices start at $2000 (projectors) or $2500 (rear-projection sets) and climb to more than $10,000. With a projector you'll get 72in to 104in display, but there are some drawbacks. First, the room needs to be dark, or at least have low levels of light. Second, you have two projector technologies to choose from: LCD, which is more affordable but produces a raster effect on the screen, and DLP (digital light processing), which does not.

However, cheaper DLP projectors can display rainbow-coloured artefacts, thanks to slow filter wheels separating the colours in the light spectrum. Try moving your head as you watch the projected image to see how much it annoys you.

Projectors also need good display screens. There are several types (silver-backed and grey-backed ones) suitable for different light situations. Talk to your retailer about this, but do not expect the freebie screen that comes with your projector to be the right one for your needs.

Also, bear in mind that projector lamps are expensive to replace. They last from 1200 to 2000 hours (depending on contrast and brightness settings) and new ones cost from $600 to $1000. Front projectors also usually need a separate TV tuner. You will probably need advice on the ideal screen size/viewing distance ration for the best image display.

Back-projection screens, where the image is projected towards the viewer against a semi-transparent screen in a large box, are well-priced and generally include the TV tuner and speakers. Take a good look at them before buying, however. Back-projection screens are bulky: will one fit in your room?

Also, check the viewing angles (sideways and up-and-down) plus the uniformity of the screen brightness and the colour reproduction, which, despite advances, still is not as good as other display technologies.

Plasma: big and slim but expensive, 32in and bigger.
Prices range from $6000 to $8000 for 32in models; $10,000 and beyond for 40in and larger. The sexiest screen of them all is the plasma. It's big - anywhere from 32in to 63in - and slim, unlike CRTs. Also, plasma screens are bright and have almost as good image quality as CRTs.

You can hang one on the wall, thus a plasma display can be much less obtrusive than other large screens.
However, plasma screens are fragile to handle, and heavy. It's probably best to get a plasma screen installed by a professional. Try to avoid shifting it after it has been installed.

The drawbacks to plasma screens are the hefty prices, and the lack of tuner and speakers in most cases. In other words, factor in a good deal more than just the price of the screen for a total audio-visual solution.
If you're going to go for a plasma screen, it doesn't make sense to skimp on the rest of the gear. Get a good tuner/DVD as well as amplifier and speakers.

LCDs: flat and even thinner, up to 40in
These range from $3800 for 23in units. LCD screens are becoming the standard for computer screens, and are starting to appear as TVs too. Despite the large screen size, LCDs are slim and light compared with CRTs.
LCDs consume less energy than CRTs, and are usually bundled with a TV tuner.

Image quality has improved lately. Today's LCDs are bright and have rich contrast; you no longer need to pull the curtains and turn off the lights to see the picture. Furthermore, prices for LCDs have come down greatly over the past year, to almost CRT levels.

Even so, they aren't quite as good at reproducing moving colour images as CRTs: you really need a response time of around 16 milliseconds to avoid the "ghosting" artefacts which happen when objects on the screen move quickly - contrasty scenes like explosions in action movies, for example.

LCDs also suffer from limited viewing angles. While the sideways angles on newer screens are good, check the up and down angles as well. Many LCDs have to be at eye level, unlike CRTs.

Buying tips

Pick the right display for the room

If you have a bright room, forget about projectors which require dark or low-ambient light. Instead, go for a CRT TV, wide-screen or normal, or a plasma display which are brighter and can cope with ambient light better.

Bigger isn't always better

That 32" TV, 72" projector screen or 40" plasma display looks manageable on the shop floor, but at home they can fill up the whole room or wall.

Quality in, quality out

A high-resolution big screen will show the bad image quality that a cheapo DVD player from the supermarket gives. Add a better input source and consider a good set of speakers.

Try it out

Ask the shop to plug the TV into a single video source to assess image quality.

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