Andy Westlake tries out an unusual compact camera with a fixed ultra-wideangle lens in his Sigma dp0 Quattro review.
Sigma dp0 Quattro review – Autofocus
In good light, the dp0 focuses pretty quickly and accurately. You can move the focus area freely around the central region of the frame, across about half the image width and height, or use a quicker-to-select nine-point mode. It’s possible to change the size of the focus box in three steps, and face detection AF is available.
Under low-level artificial lighting, though, the Quattro’s AF starts to falter. In this case, switching to manual focus may well be the most reliable approach. This can be done quickly by pressing the up button on the D-pad, and a magnified view is available for accurate focusing.