Olympus E-5 Dynamic Range (JPEG)
Our Dynamic Range measurement system involves shooting a calibrated Stouffer Step Wedge (13 stops total range) which is backlit using a daylight balanced lamp (98 CRI). A single shot of this produces a gray scale wedge from the camera's clipped white point down to black (example below). Each step of the scale is equivalent to 1/3 EV (a third of a stop), we select one step as 'middle gray' (defined as 50% luminance) and measure outwards to define the dynamic range. Hence there are 'two sides' to our results, the amount of shadow range (below middle gray) and the amount of highlight range (above middle gray).
To most people highlight range is the first thing they think about when talking about dynamic range, that is the amount of highlight detail above middle gray the camera can capture before it clips to white. Shadow range is more complicated; in our test the line on the graph stops as soon as the luminance value drops below our defined 'black point' (about 2% luminance) or the signal-to-noise ratio drops below a predefined value (where shadow detail would be swamped by noise), whichever comes first.
The E-3 has a relatively restricted dynamic range compared to most of its competitors, but the E-5's 12MP sensor is a lot more capable. As you can see from this graph, at ISO 200, the E-5's dynamic range is a close match for its nearest competitors at default settings. However, with ADL on (default 'normal', shown here) the Nikon D7000 has exceptional dynamic range in highlight areas, and both the Canon EOS 7D and Pentax K-5's highlight dynamic range are improved by turning ADL/Highlight DR 'on'. With these various features enabled, the 7D, D7000 and K-5 outstrip the E-5 by around one stop of highlight dynamic range. The E-5's 'auto' gradation setting extends highlight dynamic range by roughly 1EV but this comes at the expense of decreased shadow dynamic range (and thus increased noise in midtone and shadow areas). This isn't a problem with the more advanced sensors of the K-5 and D7000.
Base versus 'Recommended' ISO
Like previous E-series cameras, the Olympus E-5 has a nominal base ISO sensitivity setting of ISO 100, but it's 'recommended' base is ISO 200. Olympus calls settings below ISO 200 'low noise priority' settings, and although they are not labelled as such, ISO 160, 125 and 100 are in fact extension ISO settings, which offer less dynamic range than the 'recommended' base of ISO 200. Our graph clearly shows this - see how much sooner the ISO 100 (blue) line clips to white than ISO 200. For this reason we would always recommend sticking to ISO 200 if possible, and using a neutral density filter if longer exposures are called for.
The E-5's gradation setting produces images in low or high keys, it does so by modifying the tone curve as well as the exposure (around a third of a stop under for Low Key and a third of a stop over for High Key). To show the difference in tone curve more clearly for this graph we adjusted the exposure manually to match the middle grey as closely as possible. As you can see the Low key pulls down the shadows a little, whereas the high key pushes up the highlights a little. Overall dynamic range remains the same whichever setting you use. The auto mode does some serious lifting of the shadows and can introduce noise issues (we'd advise shooting raw if you want to do this kind of tonal adjustment).