Sigma SD10 review: Sigma SD10

Intro
Sigma's SD10 is the follow-up to the company's flawed but interesting SD9 digital SLR, which made exceptionally sharp photos in good light. The SD10 incorporates an upgraded Foveon X3 sensor, a three-layered imager with 3.4 million pixels and 10.3 million photodetectors. The new sensor partially overcomes the SD9's biggest weakness, which was its lack of high ISO sensitivities for low-light photography. But Sigma failed to correct most of the SD9's design and performance flaws, and the SD10 remains substantially less versatile and well rounded than competing dSLRs. The Sigma SD10's design is nearly identical to the SD9's, meaning that it's bulky, boxy, and homely. The 2-pound camera's metal chassis is surrounded by a black, polycarbonate body. Its size and squared-off shape make it a bit less pleasing to grip and handle than other dSLRs we've used.

Though its control placement is acceptable overall, and the menu system is clearly labeled and easy to navigate, our other objections to the SD9's design flaws still stand: the shutter-speed dial is hard to reach without taking your hand off the grip, and the skimpy viewfinder information display doesn't show the metering mode, the white-balance setting, or the number of shots remaining.

The SD10's feature set is mostly the same as the SD9's, but Sigma, or rather Foveon, did make one critical improvement: The camera's upgraded X3 sensor is now fitted with microlenses over its pixels, which increases its light-gathering power. That translates directly to the ability to set the camera's sensitivity as high as ISO 1,600. (The SD9 was limited to ISO 400.) The minimum sensitivity setting remains ISO 100. The microlenses also make longer exposures possible--as long as 30 seconds at all ISO settings.

The camera's exposure, white balance, and metering system is fairly comprehensive and includes all four standard exposure modes, custom white balance along with seven presets, and three light meters--eight-segment evaluative, center-weighted, and center spot. Exposure compensation to plus or minus 3EV now works in 1/3EV increments instead of the SD9's 1/2EV steps.

You can capture images only in raw format, so if you have a need for quick JPEGs, buy a different camera. The included Sigma Photo Pro 2.0 software--actually written by Foveon--is a powerful raw-processing application that makes reasonably quick and easy work of fine-tuning exposure, contrast, color balance, and color saturation. A nice new feature in version 2.0 is X3 Fill Light, which does a good job of brightening shadows without overexposing midtones and highlights.

Only Sigma SA-mount lenses are compatible with the SD10, but that's hardly a limitation. Sigma makes more than 40 different SA-mount lenses in focal lengths ranging from 8mm to 800mm. The size of the SD10's X3 sensor gives the camera a 1.7X lens-conversion factor, meaning that lenses used on the SD10 will capture the same field of view that a lens of 1.7 times greater focal length would capture on a 35mm camera. To combat the irritating problem of dust collecting on the sensor, which plagues many other dSLR cameras, the SD10 has a transparent protective cover just inside the lens mount.

The SD10 has no built-in flash, but the camera's hotshoe will accept powerful external flashes, including two Sigma TTL-dedicated strobes. Flash-sync speed is a decent 1/180 second.

Like the SD9 before it, the Sigma SD10 offers adequate performance but still lags a step or two behind the competition. Shutter delay varies from about 0.3 second to 1.5 seconds with autofocus, and it's about 0.2 second with manual focus. Shot-to-shot time is slightly more than a second. In continuous-shooting mode, the camera fires at 2.2 frames per second for a six-shot burst, after which a 7-second buffer stall sets in. These figures range from mediocre to poor for a dSLR.

The SD10's autofocus system is a throwback to the early 1990s. It hunts around too much in both good light and bad, and it can't track moving subjects that other midlevel dSLRs handle easily. This, combined with the unimpressive numbers mentioned above, makes the SD10 a bad choice for sports and action shooters.

The camera's "sports finder" viewfinder shows roughly a 25 percent wider field of view than your image will actually record. The area that won't be captured is clearly distinguished by a semitransparent gray mask. We liked the ability to see what's just outside the frame area, but the actual image area is fairly small in the viewfinder, which makes manual focusing more difficult. The camera's LCD is sharp and reasonably easy to use for reviewing images, even in bright light.

Unlike the SD9, all of the SD10's digital and mechanical operations are powered by one battery system--either two CR-V3 lithium batteries or four AA cells.

Clearly, the Sigma SD10 is made or broken by the photos its Foveon X3 sensor produces. The X3 is unique because each of its pixel locations contains three vertically stacked photodetectors: one to record red light, one for green, and one for blue. In contrast, all previous single-shot color image sensors use one photodetector at each pixel location with a checkerboard pattern of alternating red, green, and blue filters overlaid on the pixel array. Such chips thus capture only one primary color per pixel and construct full-color images by interpolating the two missing color values for each pixel from the data gathered by adjacent pixels. For more information on the X3, see Foveon's Web site. Foveon claims that compared to conventional imaging chips, X3 sensors will provide much sharper pictures with better color detail and fewer color artifacts such as moiré.

Our tests, both with the SD9 and with this model, bear out some of Foveon's claims. With well-lit subjects that contain very fine detail--finely woven fabrics and highly detailed landscape or architecture shots, for example--the SD10 often shines, making sharper pictures than any we've seen from conventional sensors with twice the pixel resolution. And the X3 sensor is indeed resistant to color artifacting, especially the kinds of moiré that can plague shots of clothing and hair. On the other hand, we did note frequent artifacts--usually thick, blue fringes--around overexposed highlights. Colors in our SD10 test shots were accurate and vivid at the Photo Pro software's default settings.

But what about noise? This was the bugaboo of the SD9, which was worse than the competition at ISO 100 and rendered shots largely unusable at higher sensitivities. The new microlenses on the SD10's sensor make a modest dent in this problem. Our test shots at ISO 100 are very clean--no room for complaint--and they still look pretty good at ISO 200. Significant noise is visible in the shadows by ISO 400--an especially irksome, blotchy, green/magenta discoloration--but some folks might not object to it at smaller print sizes. By ISO 800 and 1,600, our shots were essentially ruined by green/magenta yuck. The noise from settings of ISO 400 and higher also causes a progressive loss of detail. Bottom line: The highest usable sensitivity of the SD10 is about 1EV or 2EV greater than with the SD9 but still far lower than most of the competition.