Conventional sensors have a limited dynamic range. This means that high-contrast scenes may have solid black shadows, blown highlights, or both, depending on the exposure compromises you and the camera make.

This happens because the individual pixels, or photosites, on the sensors can only cope with a certain brightness range. At one end of the range, they don't capture enough photons to register any kind of signal; while at they other they capture so many that they're saturated.

What you need is a sensor with different-sized photosites: larger ones for everyday photography; and some smaller, lower-sensitivity sites for hanging on to detail in highlights. Fujifilm's SR sensor is the only one to tackle this issue.

Its combination of large S-type pixels and smaller R-type pixels offers a dynamic range up to 400 per cent wider than that of conventional sensors. The FinePix S5 Pro uses this SR sensor, as did its predecessor, the S3 Pro, and the design has also been tried out in a couple of Fujifilm compacts.

How many megapixels?

The S5 Pro has 6 million 'S' pixels and 6 million 'R' pixels. In older designs they were 'paired', but now they're interleaved on the sensor surface, so it's even harder to say whether this is a 6MP or a 12MP camera. By default, the S5 Pro outputs 12MP files, and because these pixels don't share the same physical location, we've referred to it as a 12MP camera.

The proof lies in prints, not pixel values. The S5's colours are excellent and its rendition of skin tones is somehow richer and more 'open' than any other camera's. Its increased dynamic range is apparent, too; not just in the extra highlight detail it retains but in the smooth tonal transitions at these brightness extremes. However, as with the S3 Pro before it, the internal JPEG processing doesn't quite do justice to the extraordinary level of highlight detail dormant in the RAW files.

Annoyingly, you don't get RAW conversion software with the camera. Or you do, but it's only a version built into Fujifilm's basic FinePix viewer. This can convert RAW files using the settings dialled into the camera at the time of shooting, but it doesn't offer the 'reprocessing' options found in Fujifilm's HyperUtility software (a £100 optional extra).