A digital compact camera with a big sensor and optics to match Sigma’s revolutionary DP1 is different in concept execution and how you use it. Report by Paul Burrows.

With its all-metal squared-off bodyshell, Sigma’s DP1 looks like a classic and feels like a classic… only time will tell whether it becomes a classic, but the potential is there.

Fans of the British TV series Yes Minister will understand the implications of describing a decision as “courageous”. Sigma’s DP1 is courageous, which means it could be the start of something very big or… well, history will record it as being little more than an interesting exercise.

Not only has Sigma created a completely different sort of camera with the DP1 – a digital compact with an ‘APS-C’ sensor and a prime wide-angle lens – it’s chosen to use a Foveon threelayered imager and skew the performance to RAW capture. Courageous indeed, but once you ‘get’ the DP1 – probably just after you’ve processed your first batch of RAW files – you’re thoroughly addicted. The big question is whether there’s enough photographers around the world who will understand just what Sigma is offering them.

For one reason or another, it’s taken around 18 months for Sigma to bring the camera to market and in that time the expectations have simply increased. Thus the DP1 arrives with a lot to live up to, especially as there have been some interesting developments at the upper end of the ‘mainstream’ compact camera market in the interim (most notably Ricoh’s GR Digital models, Canon’s PowerShot G9 and the Leica D-Lux 3, which even looks very much like the Sigma). However, the DP1 is quite different from anything else… in fact, it’s different from anything we’ve ever seen before in the digital camera world. However, it’s an indication that the market is maturing nicely and niches are emerging, but Sigma is still going out on a limb with this. That said, there is now a definite gap between the D-SLRs and the digital rangefinder designs which, let’s be honest, haven’t really set the world on fire so far.

Size Matters

What’s most significant about the DP1 is that it uses an ‘APS-C’ format sensor rather than the tiny little chips that are installed in all other compacts (so it’s six to seven times larger in imaging area).

Consequently, Sigma labels it “a full spec compact digital camera with all the power of a DSLR”. There’s some justification in this claim, as the DP1 is fitted with the same device as Sigma’s SD14 (or one very similar), namely a Foveon-type CMOS which employs three colour layers rather than the tradition Bayer pattern filtration.

Each layer comprises 4.69 million pixels – arranged as 2652x1768 pixels – which gives, theoretically at least, a total resolution of 14.07 megapixels (i.e. 4.69x3). However, as with the SD14, not everybody accepts that the Foveon sensor’s vertical arrangement of the pixels results in a tripling of the effective resolution. By the industry’s own standard of determining effective resolutions, it’s technically a 4.7 MP device. However, given there’s a comparatively small number of pixels arranged across the sensor’s surface, they’re a reasonable 7.8 microns in size, which bodes well for both dynamic range (higher) and noise levels (lower).

The imaging area is 13.8x20.7 mm (giving a native aspect ratio of 3:2), which results in a magnification factor of 1.68x to give the 35mm format equivalent. This means that the DP1’s 16.6mm f4.0 lens has an effective focal length of 28mm, which represents a good ‘general purpose’ wide-angle. It may not be wide enough for some, especially anybody yearning for a digital equivalent of the wonderful Ricoh GR21, but it works in terms of overall usefulness, the size of the lens and, of course, the price tag. Optics are obviously Sigma’s strong suit, so the DP1’s lens incorporates similar technologies to its SLR lenses, including a large-diameter aspherical element for the correction of distortion and super multi-coating to deal with ghosting and flare. Of necessity, the lens barrel protrudes from the otherwise angular bodyshell, and it’s capped with a conventional cap, albeit it one with a bayonettype fitting. A little disappointingly, the lens cap is plastic rather than metal, which would better fit in with the rest of the DP1’s character… although Sigma isn’t deliberately going ‘retro’ with the design, it’s just that straight edges, corners and black-finished metal all add up to a more ‘classic camera’ look.