Apart from its unique sensor the DP2s has several other unusual design features, the most obvious being the lens. It has a fixed-length (i.e. non-zoom) lens with a focal length equivalent to 41mm and a maximum aperture of f/2.8. This may seem like an odd choice, since the trend these days is for ever-wider focal lengths, but 41mm is close to the old SLR standard of 50mm, and produces a perspective that is very similar to that of the unaided human eye. As a result photos look very natural and optical distortion is kept to a minimum. The aspect ratio of 3:2 is the same as 35mm film and most DSLRs, rather than the 4:3 ratio more common in compact cameras. The DP2 has the same lens, but the DP1 has an f/4 lens equivalent to 28mm.
Physically the DP2s is almost identical to its two predecessors. The body is a rather plain looking matt black rectangular box with straight sides and right-angled corners, with the lens barrel protruding just less than an inch from the front when folded. The body is all metal and the build quality is generally very good, although the controls do feel surprisingly cheap for such an expensive camera. The DPS2 is large for a compact and surprisingly heavy, measuring 113.3 x 59.5 x 56mm and weighing 291g including battery and memory card. The large body is easy to hold, and a textured area on both the front and the back provides some grip, but the control layout is rather awkward. The two buttons in the upper right are poorly placed, and the thumbwheel on the edge of the top plate, which is used to adjust focus in manual mode, is also a bit fiddly. Some of the controls can be reassigned, but I hope that Sigma has a good re-think of the control interface for its next new model, perhaps replacing the focus thumbwheel with a rotary bezel on the lens barrel.
The menu system is also quite clunky and looks a bit dated by recent standards, and it is not helped by the relatively small 2.5-inch 230k LCD monitor. The monitor view can be magnified for manual focusing, but it's not really sharp enough for this to be particularly accurate. The monitor is at least quite bright, but the reflective surface can make it hard to see in bright sunlight.
We're so used to seeing 720p HD video as a standard feature on new compacts it's rather a shock to discover that the DP2s can only manage 320 x 240 pixel resolution with mono audio, albeit at 30fps. At least there's no need to worry about optical zoom in video mode.