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 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.
Dynamic Range Optimization feature
The A200 offers the same Dynamic Range optimization as the A350 (and the A100 before that). There are two modes of DRO - Standard and Advanced Auto. In standard mode, the camera will try to reduce the contrast of the image when it identifies very high contrast in the scene being shot. This tries to ensure that the highlight and shadow detail aren't all pushed to white and black, and that the image more accurately represents what the photographer saw. Advanced Auto takes this a little further and, upon being confronted with a subject with extremes of light and shade, tweaks the brightness and gradation in different parts of the image to give a balanced result.
We found the impact of DRO on the A200 quite subtle to say the least. Both DRO modes measurably, and just about visibly, lifted the shadows but the effect is very discreet (it appears to be marginally stronger in Standard mode than in Advanced mode). That's not necessarily a bad thing as your DRO images certainly won't look overprocessed. If you want more of a wow! effect, you can also generate it in post-processing.
DRO doesn't appear to interact with the camera's exposure metering, so it makes no additional attempt to retain highlight information - it's all about the shadows. As a result, users who shoot exclusively in RAW mode will not see any effect of DRO (it's a post-shot processing step so it only appears in JPEGs). The included software doesn't allow you to simply apply the same DRO effects to RAW files, instead giving two sliders to control its effects on shadows and highlights.
|DRO Advanced Auto|