The Sigma SD15 is a digital SLR to take on the Canons and the Nikons, with Sigma's proprietary Foveon sensor technology
Sigma is best known for its high-value lenses, often bought for use on DSLRs from leading brands such as Canon and Nikon. More recently the Japanese company started making its own camera bodies and even a high-end compact camera. But in a crowded market, has it got enough to distinguish itself from the competition?
While the basic form factor and operation are broadly similar to what you’d expect of most modern DSLRs, Sigma does stand apart by its adoption of an unusual image technology, the Foveon X3 sensor. In contrast to most sensors, Foveon technology uses stacked photodiodes to capture the RGB elements of light separately. With less filtering required, it’s supposed to improve light-gathering performance and reduce colour artefacts.
Supplied as a body-only for £899, we used the SD15 with Sigma’s own 24-70mm f/2.8 DG MACRO lens, which sells separately for around £450.
In use, we found the Sigma SD15 to be less comfortable to operate than most DSLRs, with controls not falling easily to hand. When in aperture- or shutter-priority mode, for instance, you’re required to negotiate a stiff dial around the shutter release to adjust exposure, and in full manual you must simultaneously press an awkward Av button on the body back to adjust aperture.
Likewise ISO adjustment requires you to hold in a button on the back of the Sigma SD15 while trying to turn the same recalcitrant dial.
The top LCD info panel is not especially informative. It tells you shutter, aperture, exposure, meter mode, battery and available shots – but for details such as ISO and white balance, you’ll need to activate the rear screen from the ‘i’ button on the camera body. The rear display is bright and clear enough though. Like most DSLRs, framing a picture on the Sigma SD15 is only possible through the viewfinder. Continuous shooting was rather slow too.
Build quality is strong enough from the all-plastic chassis, but quite hefty at 774g with battery but no lens. Combined with the 24-70mm lens, all-up weight of this Sigma SD15 and lens combination rises to just over 1.5kg. While there’s no identifiable issues with construction, it doesn’t have quite the feel of quality from a comparable camera such as a Canon 40D.
Ultimately, picture quality was a little disappointing. Noise levels were suitably low (at low ISOs at least), and colours well balanced in well-lit scenes - yet entirely lacklustre in underexposed shots. Auto white balance often left unwanted casts.
We found the less-than-comfortable ergonomics meant we had to work harder to get decent results. And even the more successful in-focus and well-exposed pictures lacked the crispness and vibrancy that a camera at this price should command.
Note that while the usual RAW and JPEG options are offered on the Sigma SD15, the unusual Foveon format is not supported by Apple, so Mac users must turn to Adobe or use Sigma’s own rather slow software.
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