Olympus E-PL2 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.
Like previous E-series cameras the E-PL2 features Olympus's Shadow Adjustment Technology (SAT) which is activated by setting the 'Gradation' mode to 'Auto'. The camera underexposes by roughly a third of a stop to protect the highlights and then performs a tone-curve adjustment, lifting the mid-tones and shadows. Overall it gives you just about 2/3 stop more highlight DR and also some extra shadow detail. The downside is that doing so can noticeably increase shadow noise even at low ISO settings, so you should arguably not leave it turned on at all times. As with all Olympus's recent SLRs and E-series cameras there are two other Gradation options; High Key and Low Key.
The E-PL2 also has Olympus's usual selection of Picture Modes that can be altered depending on the subject you're shooting and the look you wish to achieve. However, all modes use roughly the same tone curve and are clipping at the same point in both the highlights and the shadows (the differences here are tonal, not contrast).
On previous Olympus models the base ISO was 100. This produced around a stop less dynamic range in the highlights than ISO 200, which is why we recommended not to use it to avoid clipped highlights. On the E-PL2 Olympus has now done the sensible thing and removed the ISO 100 setting entirely. As a consequence all ISO settings clip highlights at approximately the same point. Just be aware that Auto Gradation, even when activated, appears to be not working at ISO 3200 and 6400. As a consequence the tone curve at these settings is the same as Normal Gradation.