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| Click photo for more images of the Sigma DP1. |
Serious photographers tend to look down on compact cameras. But would they change that attitude for one that delivered the same image quality as a DSLR, yet allowed them to travel light? Sigma believes so -- and that they'll pay a premium for its new compact DP1 ($800, street).
It's too soon to say whether the DP1 -- with its handsome good looks, single-focal-length lens, and slip-on, rangefinder-style viewfinder -- will garner a cult following like the classic 35mm Contax T2 and Konica Hexar compacts, more recent high-end digital compacts such as the Ricoh Caplio GX100 and Panasonic Lumix DMC-LX2 (a less-expensive version of the Leica D-LUX 3), or even Sigma's own SD14 DSLR. But we couldn't wait to put the DP1 to the test in the Pop Photo Lab and the field -- especially after waiting a year and half for it since it was announced.
The delay was predictable, as Sigma was very deliberate in developing the DP1. It has a tough, yet slim, die-cast aluminum body (though no weather or dust seals), a 9-zone (all cross-type) autofocus system, and full manual metering and exposure controls. Most important, it's the first compact to use a DSLR-sized sensor.
Uncommon sensor
Most compacts use smaller CCD or CMOS sensors (usually 7-9.5mm diagonally) whose pixels are just 2-3 microns wide, and use a striped or Bayer-pattern RGB filter array to help create a color image from black-and-white-sensitive pixels. At 24.9mm diagonally, the DP1's Foveon X3 Direct Image sensor measures far larger than most compact camera sensors. It also boasts 7.8-micron pixels (typical of 8-10MP DSLRs). Cameras with larger pixels tend to be more sensitive to light and have better noise performance at higher ISOs.
In addition, Foveon X3 sensors use a three-layered approach to capturing red, green, and blue information from a scene, similar to the layers in color film. In the DP1, each layer contains an array of 1768x2652 pixels (4.7MP), which Sigma and Foveon add together for 14.1MP. Claiming the DP1 has a 14.1MP sensor is controversial, since it's not in keeping with certain industry standards, such as CIPA's Effective Pixel rules, which would put it at 4.7MP.
Our Lab tests of the DP1 show that images shot in RAW and converted to TIFF files using the supplied Photo Pro 3.1 software capture 1810 lines of resolution at ISO 100. That rivals images shot with most 8-9MP compacts and DSLRs, and it's just slightly below the Sigma SD14 (1900 lines). While not rivaling the 2350 lines captured by the 14.6MP Pentax K20D, resolution is far better than the typical 5MP camera.
The DP1 doesn't stop there. It outguns every compact camera we've tested when it comes to noise control in RAW files, starting with an Extremely Low rating (1.0) at ISO 100 and topping out at Low (1.7) at ISO 800. That's significantly better at ISO 800 than the noise levels from the 10.3MP Ricoh Caplio GX100 (Unacceptable, 3.95) and Canon PowerShot G9 (Moderate, 2.6). It even beats the Sigma SD14 at ISO 800 (Moderately Low, 2.3).
Color accuracy was also stellar, with Excellent ratings (6.4 Delta E at ISO 100) all the way through ISO 800. Shadow and highlight detail? Decent in properly exposed images, but highlights started to blow out at 1 stop overexposure and on flash-lit subjects within a few feet of the camera. Despite the slightly narrower dynamic range and exposure latitude compared with RAW images captured by most DSLRs, though, the DP1 is the first in its class to earn an Excellent image quality rating from ISO 100 to 800.
Compared with its RAW shots, the DP1's JPEGs show slightly lower resolution, higher noise, and less shadow and highlight detail at all ISOs. It can be set to capture only either RAW or JPEG, not RAW + JPEG. If you stick to RAW for its image-quality advantage, have plenty of storage space on your computer: When using the Double Size RAW setting (we recommend it to get the most detail), 16-bit TIFF files will take up 106MB on your hard drive, due to generous interpolation. A comparable-resolution 9MP digital camera produces a 54MB TIFF at 16 bits.
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