Camera can snap now, focus later

Images from Lytro
Image caption Users can choose what they want to focus on after the image is taken

A digital camera that allows photographers to focus their pictures after taking them has gone on sale.

Rather than recording a single version of an image, the Lytro captures data about the intensity and direction of all the light entering its lenses.

That information can be reorganised later with the option to change which parts are blurred and which are sharp.

The "light field" technology was developed by company founder Ren Ng while he was at Stanford University.

Image caption The Lytro looks nothing like a conventional camera

It is, in some ways, analogous to the practice of shooting RAW images with a current generation digital camera.

In that example, the device records all of the light falling on its sensor without running it through processes such as colour balancing or sharpening. These can be applied later on a computer.

Similarly, by recording the light field passing through many tiny micro-lenses in the Lytro, the action of merging these to create a single flat image can be applied as a post-production effect.

The phrase light field was coined by Russian scientist Alexander Gershun in 1936. Work on developing capture mechanisms began to gain momentum during the 1980s and 1990s.

On its website, Lytro has published Mr Ng's 2006 university PhD thesis outlining his approach, which ultimately led to the commercial product.

In a press statement, Mr Ng said: "Light field photography was once only possible with 100 cameras tethered to a supercomputer in a lab.

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Media captionBBC Click looks at Lytro ahead of its launch

The Lytro's image sensor is capable of capturing, according to the company, 11 megarays of data.

However, it is understood that megarays do not translate to megapixels, and final image quality may be considerably less than that of conventional digital cameras.

The camera is also capable of producing 3D images, a feature which will be added at a later date.

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