Sigma is known for its third-party lenses for popular digital SLR cameras, as well as a modest line in complete cameras too.
The Sigma DP1x is positioned as professional compact camera, with high-quality optics and good sensor, in a no-frills metal case.
Unusually for any compact, the non-removable lens has no zoom function whatsoever. There are two telephoto-style zoom buttons on the back face, but they only serve to digitally zoom in and out on shot pictures (and also double up for exposure controls).
At heart is a proprietary Foveon X3 sensor from Sigma, a large CMOS device far larger than used in most compacts. Sigma's unique sensor tech claims to offer better image quality than any other brand's sensor, thanks to direct-image processing that doesn't require RGB filters to create full-colour output.
The Sigma DP1x camera is unashamedly low-tech in its design and features. That is, it doesn't offer the common consumer treats like smile sensing, panorama scene-stitching, GPS tagging or high-definition video.
It doesn't even include preset scene modes, although you can create your own user presets. Also absent is any image stabilisation.
It does offer RAW mode, as well as RAW+JPEG for photographers who want to extract the best from captured photos.
The mode dial on top resembles a DSLR's, with MSAP settings for manual, shutter- and aperture-priority, and program modes.
A rather slow auto-focus is joined by a manual focus option, using a small thumbwheel to adjust. With only the rear to LCD to compose, you need to zoom in for manual focusing, by first pressing the OK button in the centre of the five-button compass rose.
The 16.6mm F4 lens on the Sigma DP1x has a slight wide-angle effect, able to record an expansive scene, although there is some geometric distortion apparent toward the image corners.
With the attention on professional control rather than consumer bells and whistles, we found the Sigma DP1x a difficult camera to operate.
Exposure was often a hit-and-miss affair on the Sigma DP1x despite our patient flipping through the three metering modes and painstakingly adjusting exposure in either M, S or P modes. Many pictures came out badly over- or under-exposed – and this is despite the author's hard-earned experience of using the equally obstinate Sigma DP2 compact.
We hoped that with a large sensor and good quality glass, convincingly high-quality pictures wouldn't be too hard to achieve this time. In reality, the raw quality available disappointed.
The sensor is not especially sensitive, and often needed ISO speed set to at least 400 to capture indoor scenes without blurring.
Unfortunately, even at ISO400, noise levels were higher than we'd hope for a pro-level camera. There is a built-in flash, but it's very underpowered for any subjects more than a thre or four feet from the camera.
It's also a slow camera to work with, as if its processor was underpowered, taking several seconds for captured images to appear on the rear screen.
Video quality is so poor we wonder why Sigma bothered to include it at all. At 320x240 pixels it's very low resolution, and would be bettered by a five year-old mobile phone.
It its favour, battery life was good (mitigated perhaps by the difficulty in squeezing off many shots so easily), and the camera never crashed in the period we were testing it.
We wish we could report that this Sigma DP1x camera is expensive, slow and awkward to operate; yet capable of taking stunning pictures to make it worth every penny of its asking price. Unfortunately we only found the first part of that statement to be true. As much as we wanted to coax some of the lauded pro quality from this compact, it proved slow and inaccurate to use, with so-so images to show for it. Ultimately we found image quality inferior to what can be found on cheaper, and it must be said, far more user-friendly cameras.