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.
Film Mode setting
The Panasonic G1 has nine preset film modes, six in color and three black and white. All 'film types' can be modified in terms of contrast, sharpness, saturation and noise reduction and there also two user-definable 'My Film' settings. As you can see from the graph all settings demonstrate subtly different tone curves (as each has a slightly different contrast setting) with the Nostalgic and Vibrant settings marking the extremes. They show considerably lighter and darker mid tones respectively. Changing the Film Mode (or contrast) settings makes little difference to highlight range / the 'clip point'.
ISO Sensitivity and Dynamic Range
At its standard settings the DMC-G1 delivers 8.0 stops of dynamic range at ISO 100. Highlight range extends 3.0 EV. However there is hardly any roll-off, which could lead to rather harsh clipping at the extreme highlight end of the scale. Shadow range stretches down to -5.0 EV at ISO 100. At higher sensitivities dynamic range becomes limited by increasing shadow noise. Highlight range decreases slightly as you go up the ISO range. Unsurprisingly the G1's dynamic range is not far off from what we've seen on other Four Thirds cameras.
|Sensitivity||Shadow range||Highlight range||Usable range|
|ISO 100||-5.0 EV||3.0 EV||8.0 EV|
|ISO 200||-5.1 EV||2.9 EV||8.0 EV|
|ISO 400||-5.1 EV||2.9 EV||8.0 EV|
|ISO 800||-5.1 EV||2.8 EV||7.9 EV|
|ISO 1600||-3.4 EV||2.8 EV||6.2 EV|
|ISO 3200||-3.4 EV||2.7 EV||6.1 EV|
Dynamic Range compared
As you can see at standard JPEG settings the G1 delivers a fairly similar dynamic range and tone curve to the other Four Thirds camera in this comparison, the Olympus E-520. However, the Sony A350 and Canon 450D - both cameras with a larger APS-C format sensor - produce approximately 2/3 EV more highlight range and have a more gentle roll-off.
|Camera (ISO 100)||
|Panasonic G1||-5.0 EV||3.0 EV||8.0 EV|
|Olympus E520||-5.2 EV||2.8 EV||8.0 EV|
|Canon EOS 450D||-5.1 EV||3.6 EV||8.7 EV|
|Sony DSLR A350||-4.9 EV||3.7 EV||8.6 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. As with previous reviews we settled on Adobe Camera RAW for conversion to retrieve the maximum dynamic range from our test shots.
As you can see the default Adobe Camera RAW conversion delivers less dynamic range than JPEG from the camera (a more contrasty tone curve and less noise reduction in shadows). The best we could achieve was 10.5 EV of total dynamic range. However, this only includes 0.4 EV of extra highlight range.
- ACR Default: Exp. 0.0 EV, Blacks 5, Contrast +25, Brightness 50
- ACR Best: Exp. -1.0 EV, Blacks 0, Contrast -50, Brightness 68
WARNING: Although ACR was able to retrieve the 'luminance' (brightness) of wedge steps which were previously clipped there's no guarantee of color accuracy as individual channels clip before others. This can be seen fairly clearly in the examples below. On the right the negative digital exposure compensation has revealed a little bit of extra detail in the clouds and tarpaulin respectively but the gray patches which are appearing mean that color information has been lost. There's really not a lot here to work with.
|Adobe Camera RAW default conversion||Adobe Camera RAW with -2.5 EV digital comp.|
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