I have measured this with the step chart facility in Norman Koren's IMATEST program. Imatest can be used either with JPEGs produced directly in the camera, or with TIFF files produced from camera RAW files by a suitable raw converter. I have used mainly camera JPEGs whilst Mike Collins, whom I met via the forums on dpreview, has attained greater dynamic range by specially processing a raw file taken by me.
The technique used is to photograph a grayscale wedge such as can be obtained from Stouffer. It looks like this:-
Adjacent steps in this wedge differ by 1/3rd of an f-stop. The resulting JPEG file is then input to Imatest which sees how many steps are detected by the camera, measures the strength of the signal and the noise, and calculates the density response function of the camera, its gamma, and several different figures for dynamic range.
I have done this for the EOS 5D using two different lenses and a variety of different exposures and camera to target distances. The average of these tests is given below. Four different figures are reported for the dynamic range, depending upon how much noise you are prepared to accept in the photograph. Norman Koren says that the "high quality" criterion is rather demanding, and the "low quality" criterion is an appropriate measure of "useable dynamic range" in most circumstances.
|Canon EOS 5D||Dynamic Range in f-stops|
|Gamma||Low quality||Medium quality||Medium-High quality||High quality|
So, to summarise: when taking JPEGs straight out of the camera, the useable dynamic range is just short of 10 stops and, for highest quality work, it is just short of 7 stops.
Mike Collins has obtained a larger dynamic range by processing RAW files with Adobe Camera Raw here.
Mitch Alsup explains how noise affects the dynamic range of digital sensors in a thread on dpreview here.
Camera was set at ISO 100, picture style "Standard", large fine JPEGs, automatic white balance, sRGB colour space. Target illumination has temperature 5000 degrees K. Lenses used: EF24-70mm f2.8L USM, EF70-200mm f2.8L IS.
The information above has been averaged from twelve tests. Results of the twelve tests can be seen here.
Those results are abstracted from graphs that are output in PNG form by Imatest itself. An example of those graphs is shown below. You can see the relevant dynamic range figures at the right side of Figure 2 below. For further explanation of these figures, please see the Imatest website and look for step chart.
Peter Facey, Winchester, England
20051127, updated 20060304