Dynamic range
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Dynamic range, is the range of levels of brightness than can be captured by the sensor of a camera. It is usually expressed in EV, though older books will often refer to this as "stops". When discussing scanners, dynamic range is generally described in terms of density, where 0 is pure white, and 4 is pure black, and the dynamic range of the scanner is therefore Dmax minus Dmin.
The dynamic range depends on the type of sensor and on the ISO.
Film is generally considered to have a useful range of 7 EV, although under controlled studio conditions, a range of 10 EV can be achieved with a slide, and a negative can capture 13 EV, although, in practice, it is difficult to transfer more than 11 EV to a print.
- The human eye is capable of a dynamic range of 30 EV, although not in the same scene.
- An LCD monitor can typically display about 10 EV
- Ordinary paper is typically able to show 6-7 EV, depending on the type of paper
Digital sensors are generally considered to have a lower dynamic range than film, although the Nikon D3 has been recorded with a dynamic range of 10 EV and the Nikon D3X has roughly one stop more (see e.g. http://www.dxomark.com/index.php/eng/Image-Quality-Database/Nikon/D3X), whereas older dSLRs may have had a range of just 7 EV.
The zone system was designed by Ansel Adams for managing dynamic range. In the zone system, it is assumed that the camera can capture a range of 9 EV, but that the useful, textural, range is 7 EV, whereas the true range of black to white is 11 EV.
Dynamic range does not equate to the number of bits captured.
High dynamic range or HDR is a format for recording much greater dynamic range than is currently possible. HDR images are typically created by combining a series of differently exposed ordinary images.
