Dynamic Range contd.

Active D-Lighting

One of the D60's new features is an implementation of Active D-Lighting. This, like Sony's DRO and Olympus's Shadow Adjustment technologies is designed to increase dynamic range by reducing the exposure and lifting the shadows before the JPEG is produced. As the graph below shows it works very well, adding around a stop of highlight range whilst maintaining a relatively normal tone curve.

Of course the downside is an increase in noise in the darker areas of the frame, though in practice this isn't really an issue in the kind of situations where you're likely to really need Active D-Lighting (bright and contrasty, shot at ISO 100 or 200).

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.

As you can see from the graph below there's is indeed around a stop of extra information available, the overall gain using our best settings (using ACR's Auto setting) was over three stops (including extra shadow information).

  • ACR Default: Exp. 0.0 EV, Blacks 5, Contrast +25, Curve Medium
  • ACR Auto: Exp. 0.0 EV, Recovery 25, Blacks 0, Brightness +25, Contrast 0, Curve Linear
  • CaptureNX: default settings

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.

That said, we were actually very impressed with the 'pliability' of the D60's raw files, which have enough headroom in them to allow up to 2 stops of negative exposure compensation without channel clipping (though this varies from shot to shot according to the lighting, ISO and colors involved). As the examples below show there is a real advantage to shooting raw; images that appear to be overexposed can be very successfully 'rescued' with no penalty. The middle shot shows that once you hit ISO 400 you'll see channel clipping if you try to push the raw files too far, but at lower ISO's the results are very impressive indeed (because don't forget, the D60's JPEGs have a perfectly good dynamic range as it is).

ACR default conversion ACR with -2.00 EV digital exp. comp.

ACR default conversion ACR with -2.00 EV digital exp. comp.

ACR default conversion ACR with -2.00 EV digital exp. comp.