Engineers at photography company DxO have created an accessory that lets you turn your iPhone into a 20.2-megapixel DSLR, by attaching a new pocket-sized device to one end.

Rather than clip over the iPhone’s own camera lens, the DxO ONE device attaches via the iPhone’s Lightning connector, which launches DxO’s standalone camera app and relies entirely on its own built-in optics for image capture.

The unit comprises a 1-inch camera sensor - which DxO claims is the world’s smallest 1-inch sensor - capable of shooting images at 20.2 megapixels, a much higher resolution than the 8-megapixel cameras included on current iPhones. Plus, the aperture controls look to enable some pretty gorgeous depth-of-field effects (check out this gallery on DxO’s website) and the ONE is also capable of recording video up to 1080p at 30 frames per second, or 720p at up to 120 frames per second.

At 108 grams and 6.9 cm in height, the device will add some extra chunk to your iPhone, but it's a whole lot more pocket-friendly than traditional camera equipment. No one really wants to lug around a hefty DSLR kit, lenses, and any accompanying doodads when they're travelling, so we love the idea of shrinking everything right down to pocket-size.

But all that miniaturisation comes at a cost - while the ONE might offer a lot in terms of user convenience, taking a shortcut to DSLR-style image quality on your iPhone doesn’t come cheap. The unit, which is available for pre-order online now for customers in the US, will set you back a whopping US$599. In other words, almost as much a brand-new iPhone outright.

At that kind of price, you could just opt for an actual standalone camera instead, but while the DxO ONE is certainly an expensive little add-on, it’s also an amazing testament to the power of technological miniaturisation! (And besides, we really want one.)