(Pocket-lint) - Back at Mobile World Congress in late February, Sony ppreviewed a dual camera system that was in development

That camera has now been placed into a device - the brand new Sony Xperia XZ2 Premium set to hit stores in the summer - though maybe not in the UK. For the new cameras, low light performance is at the top of the agenda. Previously, Sony didn't join the likes of Apple, Samsung or Huawei in offering a dual camera on its phones.

It did take a step forward in imaging with its other flagship devices announced this year, the Xperia XZ2 and the Xperia XZ2 Compact. Both offer 4K HDR and 960fps slow-motion capture at full HD resolution as headline features.

The Xperia XZ2 Premium camera offers video capture up to ISO 12,800 and that for still photos it will offer ISO 52,100. The key camera is a Motion Eye 19 megapixel snapper with a 25mm wide Sony G lens f1.8. There's a 1/2.3-inch Exmor RS sensor. Then there's a black and white 12 megapixel camera, again with a 1/2.3-inch Exmor RS sensor and a Sony G Lens f1.6.

Demonstrating the camera on its Mobile World Congress stand, Sony compared the new camera system with the "previous generation", although in this case they are reference devices sealed into a low light demonstration. We believe "the previous generation" must be the camera from the Xperia XZ Premium.

Sony only showed us the video capabilities and the difference between the two devices is remarkable. There's detail in the version with the new camera system which is obscured by noise in the old version; there's clear motion in the new version where there's blurred motion in the old.

As far as demonstrations go, it's pretty clear that the new is better than the old - but then that's no surprise.

What's not clear - and Sony isn't saying - is exactly how this system works on a technical front and how it is keeping those high ISOs clean. Sony does drop in the name "Fusion image signal processor", but that's about all.

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Writing by Chris Hall.