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 cameras) black to clipped white (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' 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 the camera can capture before it clips to white. Shadow range is more complicated; in our test we stop measuring values below middle gray 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.
Picture Mode options
The E-P1has 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. As you can see, everything except the more contrasty portrait mode uses 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).
The E-P1 features Olympus's tried and tested Shadow Adjustment Technology (SAT), activated by setting the 'Gradation' mode to 'Auto'. SAT - as the name suggests - works on the shadows (it has no effect on the highlights at all), dynamically lightening the darkest areas of the frame to even out contrasty scenes. The downside is that doing so visibly increases noise even at low ISO settings, meaning that we tend to leave it turned off (you can easily recreate the effect using something like Photoshop - or shoot raw and add it with Olympus Studio). As with all Olympus's recent SLRs there are two other Gradation options; High Key and Low Key.
ISO Sensitivity and Dynamic Range
As we've noted with other recent Olympus SLRs, the E-P1's 'base ISO' (ISO 100) produces considerably less dynamic range than ISO 200 (around a stop less in the highlights), and we'd not recommend using it unless you really have to - Olympus agrees, and you won't see Auto ISO going below 200. We'd still prefer Olympus to make this clearer by marking ISO 100 as being an extended ISO setting (in the same way everyone else does), as anyone making the perfectly natural assumption that the lowest ISO setting will produce the best results is going to see a lot more clipped highlights than they need to.
Overall dynamic range in camera JPEGs is pretty good, with highlight range that broadly matches the competition - not as good as the best, but certainly in the middle of the pack (interestingly it doesn't do as well as the E-620). By the time you get to ISO 800 noise has started to eat into the shadow range, but the highlight range remains admirably consistent right up to the maximum setting.
|Sensitivity||Shadow range||Highlight range||Usable range|
|ISO 100||-5.6 EV||2.5 EV||8.2 EV|
|ISO 200||-5.7 EV||3.4 EV||9.1 EV|
|ISO 400||-5.7 EV||3.4 EV||9.1 EV|
|ISO 800||-5.1 EV||3.4 EV||8.4 EV|
|ISO 1600||-5.1 EV||3.4 EV||8.4 EV|
|ISO 3200||-5.1 EV||3.3 EV||8.3 EV|
|ISO 6400||-5.1 EV||3.4 EV||8.4 EV|
Dynamic Range compared
These days there's very little difference between the tone curves or usable dynamic range of competing cameras, and the E-P1 matches similarly specified SLRs, though the Nikon D5000 and Olympus E-620 give you around half a stop more at the top end, thanks to their more gentle roll-off. We did find the E-P1 had a tendency to clip highlights in bright scenes, partly due to the tone curve, partly due to metering.
|Camera (base ISO)||
|Olympus E-P1 (ISO 200)||-5.7 EV||3.4 EV||9.1 EV|
|Nikon D5000||-4.8 EV||4.0 EV||8.8 EV|
|Canon 500D||-5.1 EV||3.4 EV||8.5 EV|
|Panasonic G1||-5.7 EV||3.3 EV||9.0 EV|
|Olympus E-620||-5.4 EV||3.9 EV||9.2 EV|
The wedges below are created by our measurement system from the values read from the step wedge, the red lines indicate approximate shadow and highlight range (the dotted line indicating middle gray).
Experience has told us that there is typically around 1 EV (one stop) of extra information available at the highlight end in RAW files and that a negative digital exposure compensation when converting such files can recover detail lost to over-exposure. To see what we could get out of the E-P1 we experimented with Adobe Camera Raw, Olympus Studio and Capture One.
With ACR and Studio we were, by flattening the curve and using negative exposure compensation, able to get just under a stop more highlight detail out of the files (though with no guarantee of color accuracy), which was consistent with our 'real world' experience.
|Settings||Shadow range||Highlight range||Usable range|
|JPEG||-5.7 EV||3.4 EV||9.1 EV|
|ACR Auto||-7.5 EV||2.8 EV||10.2 EV|
|ACR 'Best'||-6.0 EV||4.3 EV||10.7 EV|
|Studio 'Best'||-6.0 EV||4.6 EV||10.7 EV|
Looking at a typical shot with highlight clipping you can see that it is possible to pull back a little extra tonal information, but even at -1.3 EV a magenta tinge is creeping into the brightest areas.
|Camera JPEG||-1.3 EV in Olympus Studio|
In this example we've gone to the maximum negative 'exposure compensation' offered in Olympus Studio to see if it can pull anything out of the clipped areas of this slightly overexposed shot. As you can see, there's little to be gained by going beyond about 1 EV; clipped tones remain clipped.
|Camera JPEG||-2.0 EV in Olympus Studio|
|100% Crop||100% Crop|
For our last example we'll look at two shots of the same scene taken within a couple of seconds of each other at different exposure settings. The first is the metered exposure, which has blown out the bright background; the second is the same shot with 1.3 EV applied in-camera.
|Camera JPEG @ Metered exposure||Camera JPEG @ -1.3 EV|
|100% Crop||100% Crop|
Now let's see if we can get the same effect by dialing in some negative exposure compensation on our raw file:
|RAW, -1.3 EV Olympus Studio||RAW, -2.5 EV Capture One|
|100% Crop||100% Crop|
Although pulling the raw file back by 1.3 EV (so it matches the second exposure) improves things and equalizes the overall brightness of the scene, it can't bring back all the tonal information in the background, and there's still some clipping in areas that weren't clipped when using the corrected exposure in-camera. The upshot of all this is that, whilst you can deal with up to a stop or so of over exposure by shooting raw, you'll get far better results if you get it right in-camera (as usual with Olympus, the JPEGs are very well optimized and make full use of the sensor's capabilities.