Philips Cinema 21:9

This Philips TV (the 58PFL9955H/12, to give it its full model number) is wider even than most widescreen sets.

That's because it uses an aspect ratio of 21:9 (21x9 units). A normal widescreen aspect ratio is 16:9, while older standard televisions came in an aspect ratio of 4:9, or 12:9.

But even on a widescreen set, if you're watching most films you'll see black bars at the top and bottom of the screen. That's because films are usually shot even wider than 16:9, but until now it's been impractical and too expensive to produce screens that wide for home use. In fact, it's not really practical now, which is why this set costs £4,000. But Philips is pushing this shape quite hard, so it wouldn't be a surprise to see cheaper, 21:9 smaller models coming along soon.

It measures 58in across the diagonal, although that doesn't mean an enormous amount when the screen is so wide – the visible screen is 53.5in wide and 22.8in high.

Television programmes now are routinely broadcast in the 16:9 ratio, so a normal widescreen TV is fine for those - in fact it's better, because those programmes shown on this screen will have black bars down either side. There are several modes available so you can stretch or squeeze programmes to fit the screen, but some of them might lose quite a lot of the picture.

For films, though, the set comes into its own. As well as showing the full widescreen display, it also works in 3D, coming with two pairs of the active-shutter glasses required to watch in 3D. However, while colour response and brightness were good, the 3D effect was relatively poor, with lots of ‘ghosting' – even with the glasses on we could see two images of each character or object on screen, which was irritating. The effect was reduced by sitting directly in front of the screen but not eliminated, and it's not practical for all viewers to sit dead-centre.

You will need a decent source device to make best use of this TV – we tested it alongside the Philips BDP7500B2 Blu-ray player, which worked well. It will also play well from a Playstation 3 or Xbox 360 console, though both of those output games at 16:9 so you will see the black bars at the sides while playing unless you use one of the stretching modes.

It's worth noting that even if you are watching a Blu-ray disc you still won't be getting the full benefit of the screen's ability to display video in the 1080p high-definition resolution. Because films are designed for 16:9 screens the black bars at the top and bottom are hard-coded into the discs – so the film itself only occupies the middle part of the display. That means it needs to be ‘up-scaled' for the 21:9 Cinema screen, resulting in a slight drop in quality.

So the 21:9 Cinema screen is only good for Blu-ray movies: while it includes a Freeview tuner it's not ideal for watching television or playing games.

The £4,000 price tag backs up the idea that this is really a TV for the high end – for people who can afford a TV that's only for watching films.