Sigma/Foveon claim rich colour resolution from their sensors, and it's certainly the case that colours came through rich and punchy in our test images (more so than we expected, thanks to the drab-looking rear LCD).
AUTO-FOCUS: The AF hunts around a bit and can be hit and miss at wider apertures. We wanted the Sigma to focus on the main flower in the foreground here but it missed it by a country mile
Higher ISO performance was pretty good too, certainly comparable with similarly priced CMOS/CCD sensors. ISO only goes up to 800 however, which is a bit restrictive when you are shooting in low light and need fast shutter speeds. There is a built-in flash, however.
COLOURS: Don't be fooled by the drab rear LCD, colour rendition is very good, without blowing out highlights too much. The Sigma seems to have oversharpened the edges in JPEG mode though
We did notice that the metering system has a tendency to underexpose, so be prepared to adjust exposure compensation.
LENS: The lens performance is impressive for the money. It's sharp, accurate and with minimal distortion, though at f/4 max, it's not the fastest
But the big problem with the Sigma DP1s is speed. It can take around five seconds for the camera to process and save a RAW image to a typical memory card, and you can't do anything else while the electronics are whirring away.
WIDE ANGLE: The 28mm fixed lens is fine for wide angle work. Note the punchy colours, a benefit of the 14Mp Foveon sensor and the smart image processing technology
Even saving a high-res JPEG takes two or three seconds, and it's noticeably slower than a Canon or Nikon equivalent camera.
Needles to say, shooting in burst mode completely locks the camera up while the seconds tick away (and photo opportunities disappear). Another niggle is the sluggish AF, which hunts around way too long before locking on to where you want to focus.
Whatever the virtues of the Sigma DP1s, the sluggish write-times render it impractical for high-speed action and wildlife photography. Sigma can't blame the card either, as we were using a brand-new 2Gb SanDisk card – very similar to what most of the target market will be packing.