JPEG Tone Curves /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 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.

Note: this page features our interactive dynamic range comparison widget. The wedges below the graph 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).

Cameras Compared

The chart below shows the X-T1's default tone curve, in comparison to some of its immediate peers.

The X-T1 offers around 4EV of highlight range, with a relatively gentle roll-off at the top rather than an abrupt clip to white. This gives a quite natural-looking, 'flim-like' response. At the other end of the range, though, it dips down rather abruptly to black, which gives distinctly punchy images but does mean that shadows are somewhat prone to blocking up.

If you don't like this, the X-T1 allows you to tweak it's tonal response in various ways. You can change its 'Dynamic Range' setting to increase highlight range by either one or two stops (which we'll cover on the following page), and use the 'Highlight Tone' and 'Shadow Tone' controls to adjust the contrast.

Highlight and Shadow Tone options

The X-T1 allows you independently adjust the shadow and highlight regions of its tone curve, to increase or decrease contrast in these areas. This enables you to more closely match the tonal response of earlier X-Series cameras (which had slightly lower-contrast shadow responses), if you wish. The adjustment is available in two steps either side of normal (Hard, Medium Hard, Medium Soft and Soft), and the highlight and shadow options can be combined freely. In the graphs below we're showing just the extremes for clarity.

The Highlight Tone control changes the local contrast above middle grey, but doesn't have any impact on the white clipping point (which is controlled by the DR setting). Setting it towards 'Hard' can accentuate detail on a dull day, while 'Soft' can help to render more visible detail in highlights which are close to clipping. The Shadow control works slightly differently, changing the point the shadows clip to black. Setting it towards 'Hard' can suppress shadow detail in deliberately low-key images, while 'Soft' opens up the shadows to reveal more detail.

These adjustments can be combined with the camera's DR modes, either at the point of shooting or later, using the in-camera Raw converter. You can also adjust overall brightness in the Raw converter, which altogether gives a good degree of flexibility to help you produce a JPEG you like.

'New' Standard tone curve and shadow detail

When we reviewed the X100S, some readers expressed concern that the camera's default tone curve clipped more aggressively to black than the X-Pro1. If you compare the X-T1's standard 'Provia' setting to the X-Pro1's version, you can see this is still the case. Interestingly, though, the tone curve is almost exactly the same as the X-Pro1's 'Astia/Soft' setting. So the 'Provia/Standard' and 'Astia/Soft' settings now use essentially the same tone curve, differing mainly in terms of colour rather than contrast.

The X-Pro1 Provia tone curve can't be precisely imitated on the X-T1 through the use of the Shadow Tone setting (since it affects everything from immediately below middle grey, whereas the X-Pro1 Provia only differed in terms of the deeper shadows). However setting the Shadow Tone to 'Medium Soft' probably offers the closest approximation. If you're looking for that gentler, lower-contrast look, the X-T1's Pro Neg. Std film mode offers the same contrast but with a different, more muted color response. This is illustrated in the real-world example below.

Provia / Standard film mode
Shadow tone Normal
Provia / Standard film mode
Shadow tone Medium Soft
Provia / Standard film mode
Shadow tone Soft
Astia /Soft film mode
Shadow tone Normal
Pro Neg Standard film mode
Shadow tone Normal

Here we've converted the same Raw file in-camera in several different ways, to look at how the Shadow Tone interacts with the Film Simulation mode. The Provia and Astia modes both block up the shadows at with Shadow Tone set to Normal, while Pro Neg Standard reveals more detail. However it can be approximately matched using Provia with the Shadow Tone set to Medium Soft, although there are still some differences in tonality. Setting Shadow Tone to soft pulls out even more detail, but the image does end up looking a little flat as a result.