Our new 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 DMC-L10 has nine preset film modes, six in color and three black and white. As you can see from the graph below the first four (Standard, Dynamic, smooth and Nature) demonstrate subtly different tone curves (as each has a slightly different contrast setting),. The last two, Nostalgic and Vibrant, are significantly different, with considerably lighter and darker mid tones respectively, and less of a 'roll off' in highlights. Changing the Film Mode (or contrast) settings makes little difference to highlight range / the 'clip point'.
Here we have tested the extremes of the contrast setting from -2 to +2. As you can see there's no effect on the highlight range (which always clips at around 3.2 or 3.3) and only the slightest effect on the shadow range (which is marginally extended if you turn the contrast to -2). As we discussed elsewhere the range of in-camera controls - including contrast - could do with being a little wider.
ISO Sensitivity and Dynamic Range
The DMC-L10 delivers a perfectly respectable 8.4 EV (eight and a half stops) of dynamic range at ISO 100. Highlight range extends nicely to 3.3 EV, though there is only the slightest roll-off, which could lead to rather harsh clipping at the extreme highlight end of the scale. Shadow range stretches down to -5.3 EV at ISO 100. At higher sensitivities dynamic range becomes limited by increasing shadow noise, although highlight range remains the same (and the dynamic range is essentially unchanged from ISO 400-1600). Interestingly the L10 manages to capture the best part of a stop more dynamic range in JPEGs than the Olympus E-510 across the ISO range. Most importantly you get around half a stop more highlight range. The L10 may still not be as good as the best of its competitors, but it is still an improvement.
|Sensitivity||Shadow range||Highlight range||Usable range|
|ISO 100||-5.1 EV||3.3 EV||8.4 EV|
|ISO 200||-4.7 EV||3.1 EV||7.8 EV|
|ISO 400||-4.0 EV||3.3 EV||7.3 EV|
|ISO 800||-4.0 EV||3.3 EV||7.3 EV|
|ISO 1600||-4.0 EV||3.2 EV||7.2 EV|
Dynamic Range compared
As you can see the L10 delivers a very similar dynamic range and tone curve to the Sony Alpha 100 and Canon EOS 400D - the Olympus E-510 is the only real exception in this class, with around 0.7 EV less highlight range (in JPEG mode).
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 tells 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 is fairly typical you get about an extra one stop of highlight information and potentially even more a the shadow end. However see our caveat below about highlight detail maintaining color.
- ACR Default: Exp. 0.0 EV, Blacks 5, Bright. 50, Contrast 25, Curve Medium (Default)
- ACR Best: Exp. -1.1 EV, Bright. +29, Contrast -50, Recovery 25, Blacks 3, Curve Linear
WARNING: One thing to bear in mind is that 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 may clip before others.
Our experience was that in reality there wasn't that much usable headroom in the L10's raw files (unlike, for example, the Olympus E-510), and most areas that looked clipped in the JPEG were more often than not clipped in the raw file. Using negative digital exposure compensation can pull back a little detail but there is little color information, and if you go too far you'll see a magenta cast on all the recovered highlights.
This means two things; Panasonic is doing a pretty good job of squeezing all but the last half stop or so of useful highlight range out of the L10's sensor in JPEG mode - and that you need to be careful with your exposures if you're shooting any scene with a wide dynamic range.
|ACR default conversion||ACR with -2.00 EV digital exp. comp.|