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Dynamic Range

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) 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 Wizard settings

All the Picture Wizard settings have a slight influence on image brightness but appeared to share one of two tone curves. Most of the settings used the same tone curve as the Standard setting, which has a slight kink at the top of the curve to provide a slightly less harsh transition from bright tones to completely white. The Forest, Calm and Classic (Mono) modes appear to offer no such attempt to give a roll-off into the highlights.

Contrast setting

Usually, changing the contrast on a camera adjusts the 'S' shape of the tone curve - increasing contrast creates a more exaggerated 'S' shape and decreasing it straightens the curve out. The effect is the the drop from the highlights to the shadows is made more steep or more gentle, respectively. Instead, the NX10's tone curve doesn't significantly change in the highlights, instead only the mid-tones and shadow regions are affected.

The result is that, rather than a precipitating an abrupt jump in the highlights, the user can dictate how much contrast there is in the darker regions of the image.

ISO Sensitivity and Dynamic Range (JPEG)

The NX10 delivers up to 8.8 EV of dynamic range at its base ISO setting. As ISO increases, its ability to capture highlight detail changes very little but the increased noise that occurs in the shadows increasingly eats into the shadow range as the ISO increases. These figures are calculated with high ISO noise reduction turned on - turning it off reduces the ISO 3200 shadow range figure by 0.3 EV.

Sensitivity Shadow range Highlight range Usable range
ISO 100 -5.6 EV 3.2 EV 8.8 EV
ISO 200 -5.5 EV 3.1 EV 8.5 EV
ISO 400 -5.4 EV 3.1 EV 8.4 EV
ISO 800 -4.3 EV 3.1 EV 7.4 EV
ISO 1600 -3.4 EV 3.0 EV 6.4 EV
ISO 3200 -3.0 EV 3.0 EV 6.0 EV

Dynamic Range compared

The NX10's tone curve is virtually identical to that of the GF1, with them both offering a much more abrupt clipping to white than the smoother tone-curve of the Canon (though all three are capturing similar dynamic ranges, overall). The Nikon, which exposes its sensor to optimize the highlights, is able to capture detail over 0.7 EV brighter than the rest of the cameras here but, as a result, its shadow regions are noisier, meaning you get the same overall dynamic range figure.

Interestingly, the NX10 seems to be exposing its sensor differently to the Pentax K-7, which uses a very similar co-developed Samsung sensor. The NX10 has a slight kink at the top of the tone curve to give a slightly less abrupt jump between near-white and totally white, and also manages to grab an extra third of a stop of brightness.

Camera (base ISO)
Shadow range
Highlight range
Usable range
Samsung NX10 -5.6 EV 3.2 EV 8.8 EV
Nikon D5000 (ISO 200) -4.8 EV 4.0 EV 8.8 EV
Canon EOS 550D -5.6 EV 3.2 EV 8.8 EV
Panasonic DMC-GF1 -5.4 EV 3.1 EV 8.5 EV
Pentax K-7 -5.7 EV 2.9 EV 8.7 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).





Smart Range

The NX10 has the same sort of highlight-boosting approach that we've seen in many other recent cameras. The Smart Range feature is based around a different tone curve to the standard mode - amplifying the sensor less so that all tones are recorded further down the sensor's dynamic range than usual, then pulled up by the new tone curve. (At ISO 200 with Smart Range engaged, the sensor's signal is amplified in the same way as ISO 100 would be, with Smart Range turned off. Consequently, you can't drop to ISO 100 with Smart Range turned on).

The result is that an extra stop of tones are captured in the highlights but at the expense of some of the shadows becoming noisier (or, in the NX10's JPEGs, resulting in more noise reduction being applied). The great advantage of this mode is not just the brighter tones that are captured, but also the more subtle roll-off of the Smart Range tone curve, which will make the transition from detail to pure white a lot smoother and less jarring. It's interesting to compare this result (and that of the Canon 550D/T2i in the similar Highlight Tone Priority mode), with the default behavior of the Nikon D5000. However, the cost of this technique is great noise or, in the case of the NX10, more obvious noise reduction.

RAW headroom

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. However, this headroom often comes from the fact that not all color channels 'clip' (reach maximum saturation) at the same point. As a result, this recovered detail is often without color accuracy (because there's no meaningful information in the clipped channel). The amount of exposure latitude is likely to vary depending on the relative sensitivities of the three channels and the characteristics of the light under which the photos are shot but tends to be around 1EV.

As with previous reviews we settled on Adobe Camera RAW for conversion to retrieve the maximum dynamic range from our test shots.

Settings Usable range
JPEG 8.8 EV
ACR Default 6.7 EV
ACR Auto 8.8 EV
ACR Best 9.6 EV

Cameras with very gentle roll-offs in their highlights tend to have a lot of recoverable headroom because this near-white detail can be pulled down in brightness so that it's more clearly visible. The NX10's very steep tone curve means this is less likely to be the case (less of the captured data appears as near-white in the standard JPEGs), so we'd expect the recoverable range to be quite small. And sure, enough, if we try to pull a RAW file down by 1.55 EV, so that it matches the brightness of a correctly exposed image, there is some recoverable detail but not a full 1.55EV's worth and not with particularly good color accuracy.

Camera JPEG Adobe Camera RAW with -1.55 EV digital comp.
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