Is a 4K screen really worth the money?

Pixel perfect: Sony's Xperia Z5 Premium smartphone has 4K technology - but it comes at a price of �600.
Pixel perfect: Sony's Xperia Z5 Premium smartphone has 4K technology - but it comes at a price of �600.
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JUST when you’d got used to your big-screen HD TV, along comes one with an even bigger screen and better definition.

The current gold standard in viewing is 4K, sometimes called Ultra 4K. The interchangeable terms refer to televisions with a resolution of 3,840 x 2,160 pixels – which is four times that of what manufacturers are still calling “full HD”, at 1,920 x 1,080 pixels. By way of comparison, standard definition TVs display 720x576 pixels.

These sets are available from all the big manufacturers, with prices starting at a little less than £1,000. All have one thing in common, and that’s a screen of 40 inches or more. The reason is as clear as the admittedly stunning 4K picture: you don’t notice enough of a difference on anything smaller.

So the decision by those same manufacturers to put 4K screens on their latest top-of-the-range phones takes some fathoming. Surely, this is technology for technology’s sake?

Well, yes and no. It’s beyond all sensible argument that you don’t need such a high resolution screen on a device so small – yet once you factor in the viewing distance involved, the rationale becomes fuzzier.

In an average living room, it’s hard to tell the difference even between standard and “regular” high definition on a 32-inch screen, unless you’re sitting on the sofa closest to it. But hold a five-and-a-half inch phone up close, say the manufacturers, and the difference is as clear as the nose on your face. On that basis, Sony would like you to part company with £600 for its new Xperia Z5 Premium smartphone.

It’s easy to get carried away – and, of course, Sony and others hope you will be – by your screen’s pixel count, but no matter how big or small it is, you’re never going to get the best from it unless you’re viewing something intended to be seen in 4K.

You can do this by watching a 4K channel, buying one of the upcoming 4K Blu-ray players, or streaming ultra-HD from the internet.

There are few 4K broadcast channels currently available, and none if you don’t watch sport. BT Sport’s Ultra HD, with its supporting set-top box, is leading the way, and we can expect competition from Sky soon.

The BBC has indicated it will provide 4K coverage of next summer’s Olympics, but it will be a long time – if ever – before we see EastEnders in any such detail.

Blu-ray players and discs in 4K are due in the shops in time for Christmas, but prices will be high at first – and as discs are on the way out in the long term, they don’t look like a great investment.

Internet video streaming in 4K is already a more mature market, with shows like Breaking Bad and House of Cards available on Netflix, and you can watch on your phone or TV. But you’ll need fibre broadband with a speed of at least 20Mbps.

For the moment, 4K screens remain exotic rather than mainstream. To justify the cost of one you will need to watch a lot of TV – and from a very close distance.