Question: According to [DxO tests](http://www.dxomark.com/index.php/Cameras/Camera-Sensor-Ratings/%28type%29/usecase_landscape), cameras have 10 to 12 stops of dynamic range. Is that correct? Noise can completely screw some lowers values (easily resulting in loss of some stops).

Also [Norman Koren says](http://www.normankoren.com/digital_tonality.html) that a digital camera's original dynamic range can be 9 to 11 stops, but prints have "only" 6.5 stops.

In a section on dynamic range, Wikipedia says the human eye has a contrast ratio of around [6.5 stops](http://en.wikipedia.org/wiki/Human_eye#Dynamic_range). If that is the case, why is the human eye clearly much better than cameras to record scenes with high dynamic range?

Answer: 
Metaphorically, it may be due to the fact that the brain doesn't "see" a single image, but composes one based on a series of continuous "shots" from the eyes as they move around the scene.

Each of these "shots" are "taken" with variable "apertures", in order to maximize the overall dynamic range of the final "image".

You can think of the mental process as a mix of a panorama and HDR if you prefer. :o)
The main reason for this is that the human eye registers brightness on a logarithmic scale, whereas digital sensors are linear. Take a look [at this site](http://www.petapixel.com/2011/05/05/biology-for-photographers-why-is-the-aperture-scale-logarithmic/) about halfway down for more info.