This gadget is a camera, albeit one that has little in common with the vast majority of digital cameras.

The Lytro is the brainchild of Ren Ng, a Stanford University graduate whose research into light field photography won the academic institution's prize for best thesis in computer science.

The key selling point of the Lytro is that images can be focused after the fact. Unlike a conventional camera where moving optics focus incoming light against a flat plane, the Lytro camera sensor records the colour, intensity and direction of individual light rays, allowing the photographs to be reconstructed and refocused after they are captured.

The camera sports a large, sharp lens with 8x optical zoom. Zoom level is controlled by a touch sensitive slider on top of the camera which is, in all honesty, a bit of a pain to use. The touch-sensitive area is defined only by a subtle line of raised dots, and it takes several swipes across the camera to go from the widest to tightest zoom settings.

Even at the widest setting the Lytro isn't a match for most smartphone cameras, making it difficult to capture landscapes or even whole buildings in a single shot. In side-by-side testing with an iPhone, I found the Lytro would capture around one-quarter of the overall scene captured by the phone camera.

Most cameras can be measured in terms of their megapixel (MP) count - the number of individual points of light that the camera records, measured in millions. A typical modern compact camera will record 8-12MP.

By contrast, the unique way the Lytro records pictures requires a different measure - megarays. The Lytro sports a seemingly impressive 11-megaray sensor, but this produces photographs that are equivalent to just 1.2MP in old money, which is only big enough to produce a sharp 4in print.

Not only are the images of a similar size and resolution to a late 1990s digital camera, but the colour accuracy and sharpness are reminiscent of that era too; images can have a strong blue or orange cast, often look flat and suffer from excess noise or grain in anything less than bright daylight.

The Lytro camera is a great science project and Ren Ng was a worthy award winner at Stanford, but that doesn't necessarily make the Lytro a great product. At £400 there are many faster, sharper, lighter and simpler cameras on the market, leaving the Lytro in a very narrow niche - a camera that does something clever that nobody needs.