Fujifilm X10 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 Fujifilm X10 uses a default tone curve whose dynamic range extends a somewhat disappointing 3 stops into the highlight region above middle gray, lagging behind Micro Four Thirds and large-sensor compact camera models. The roll-off into the highlights is a bit on the steep side as well, providing precious little transition from near white to clipped data. Fujifilm appear to have sacrificed some highlight clipping for preservation of shadow detail. Of course, any X10 user will have DR expansion modes available. And just by switching to DR 200, you can close the gap considerably when compared to DR expansion modes on its competition.
The X10's three color Film Simulation modes show subtly different tone curves, which combine with saturation and color balance adjustments that translate into visible real-world differences, which you can see on the features page of this review. Velvia offers a dramatic contrast boost by clipping abruptly in the shadows, while Astia offers a more subtle contrast increase which preserves more shadow detail by comparison. The basic B & W mode (of which there are three additional variants) matches the default Provia's tone curve exactly. All of the modes shown here maintain the same middle gray value, meaning that whichever one you choose, the overall image exposure will remain consistent.
In a potentially confusing manner, it is possible to reap the same benefits of DR expansion in both standard 12MP mode and the purpose-built EXR DR mode up to DR 400. In the table below you can see direct comparisons between DR200 when activated in 12MP mode and when called upon in EXR DR mode, which outputs a 6MP file. The results between the 12MP and 6MP files when using the same DR settings are identical. As such, the only benefit - as it relates to dynamic range - to actually using the EXR DR mode is in very high contrast scenes that require DR 800 and DR 1600, both of which are only available in EXR DR mode. Keep in mind though that switching to EXR DR mode does allow you to use lower ISOs, which of course has the potential for lower noise levels.