Sigma SD10 Digital Camera
New Full Color Foveon X3 Pro Sensor In A Full Featured SLR

Peter K. Burian  |  Apr 1, 2004

The Continuous autofocus system had no difficulty tracking most moving subjects and the 1.9 fps framing rate (in high-res capture) was adequately fast for all but sports photography.
Photos © 2003, Peter K. Burian, All Rights Reserved

Best known for its vast line of lenses with sophisticated technology, Sigma also manufactures 35mm and digital SLR cameras. Their latest digital SLR, the SD10, is an improved version of the earlier SD9 employing an enhanced Foveon X3 sensor detailed in the technology sidebar. This is also a
full-featured camera with all of the capabilities we expect in a 35mm model targeting photo enthusiasts. Upgrades over the SD9 include higher ISO and longer shutter speed options, more reliable autofocus, especially in low light, plus support for wireless off-camera TTL flash when using two Sigma DG SA-N series flash units.

The specifications and the technology are certainly noteworthy, but how effective is this camera? In terms of performance, the SD10 is certainly competent as I discovered while shooting at an indoor Native American dance competition plus many outdoor events. In most respects, this digital camera proved to be as responsive as the 35mm Sigma SA-9 model, understandable because it shares many mechanical and
electronic components.

Conventional Capabilities
Slightly larger than some 6-megapixel cameras, the SD10 body is quite thick, with a chunky handgrip that's ideal for anyone with large hands. A well-equipped camera, the SD10 incorporates features that experienced photographers expect, including depth of field preview and reflex mirror lockup controls. All conventional features are accessed with two large knobs and familiar buttons; anyone with SLR camera experience should find this model's basic operation to be straightforward and intuitive.

Like all Sigma cameras, this one requires SA-mount autofocus lenses made only by Sigma. The camera's 1.7x "focal length multiplier" increases the effective focal length of any lens, very useful with distant subjects often precluding the need for an expensive super telephoto lens. For wide angle photography, it requires a very short lens, such as the 15-30mm or the new 12-24mm Aspherical zoom. Unlike some digital SLR cameras, the SD10 does not include built-in flash and it's fully compatible with only two accessory flash units: the new Sigma EF-500 DG ST SA-N and the EF-500 DG Super SA-N.

Evaluation: When compared to a full-featured 35mm SLR, the SD10 fares quite well, missing only a built-in flash and multiple autofocus sensors. The autofocus system includes only a central focus detection point, useful for precise focus on an essential subject element, such as the eyes in a portrait. Thanks to the improved autofocus algorithms, the camera provided reliable focusing even in the low light of an arena. In action photography, the single sensor was useful as long as a part of the primary subject remained near the center of the frame. The continuous focus system had no difficulty tracking joggers or cars moving along city streets, although the first frame of a sequence was not always sharply focused. Like some digital SLR cameras, the SD10 does not offer high-speed continuous framing for long bursts in high-resolution capture mode, but it's fast enough for a camera that was not designed for sports photography enthusiasts.

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Digital Capabilities
Some digital SLR cameras are complicated to operate because they include a vast range of digital features: a multitude of custom functions, numerous manual options, and several electronic menus. By comparison, the SD10 is quite simple because it includes only the essential digital capabilities, such as three resolution levels and eight white balance options, including Custom for use under unusual lighting. Because of the lack of complexity, I needed only 10 minutes with the instruction manual to become proficient with the digital aspects.

The camera is quick to respond, ready to take the first shot in about 1 second. Press the shutter release button and the SD10 makes an image almost instantly, except in low light when the autofocus system may take a second to find and confirm focus. In high-resolution capture mode, you can take five shots in under 3 seconds. Afterward, the camera can shoot one additional frame every 10 seconds until the buffer (a temporary storage bank) is finally full.

The large, high-resolution raw data files fill up the camera's buffer when shooting a lot of frames quickly. Occasionally, I found that the SD10 refused to respond and I needed to wait for about 30 seconds before I could shoot another image. Switching to the medium resolution mode allows for faster (2.4 fps) framing and generates smaller files that do not fill up the buffer memory as quickly. The resulting (1512x1008 pixel) images are large enough for photos that will be printed at 8x10" or smaller.

Essential Software
Because the raw data the SD10 generates must be processed and converted to an image format in a computer, the Photo Pro converter software is an integral part of the photographic process. Convenient and easy to use, this program is also incredibly fast: it will convert a
high-res file to TIFF in 3 seconds. Select the "Double" option and Photo Pro will interpolate, adding pixels to generate a 4536x3024 pixel TIFF (39MB) file in 10 seconds, still amazingly fast. More importantly, the software includes a full range of tools for modifying virtually all technical aspects of an image including a unique feature, X3 Fill Light, that mimics the effect of fill flash by lightening shadow areas.

Evaluation: Some photographers may miss certain extra digital features available with other cameras, and that's understandable. However, user-selected adjustments for factors such as color space and common image parameters are unnecessary in the SD10 because all of that is selected in the Photo Pro software. This is among the best converter programs on the market, offering an incredible degree of control over all aspects of a raw format image.

The only significant feature that's missing is the JPEG capture mode, available with most every other digital camera. Consequently, all images must be converted in the Photo Pro software, a time-consuming process when you must process hundreds of images after a vacation trip. However, serious photographers will appreciate raw capture because it produces visibly higher image quality than JPEG capture. As well, major corrections--especially for color balance, saturation, and sharpness--are more effective when made to raw data vs. a JPEG that has been processed in camera.

Image Quality Evaluation
After adjusting the raw data files in Photo Pro, with Sharpness set to level +5, most of my high-resolution ISO 100 images are excellent with great sharpness and definition of intricate detail. At 100 percent magnification on my monitor, there are no jagged edges, visible noise, or other artifacts that might degrade image quality. My only complaint is that skin tones are not always ideal; in images made in deep shade or in heavily overcast conditions, they're a tad yellow, unless carefully adjusted in Photo Pro software and then perfected in Photoshop. Otherwise, colors are clean, pleasing and faithful to the subject, particularly in images made on sunny or partly cloudy days.

Images made at ISO 400--while shooting the indoor powwow without flash--exhibit slight digital noise, reminiscent of fine grain in an ISO 400 color slide film. In ISO 800 images, the noise level is higher than average, obliterating some fine detail, but my 7.3x11" prints are still very good. Because digital noise is objectionable at ISO 1600, reserve that option for low-light situations where there's no other way to get a sharp picture.

How It Compares
Based on Foveon's claims, you would expect this camera to generate images with more resolution than a 6-megapixel camera with a conventional sensor. While I have no scientific method of testing that claim, I concluded that the SD10 produces incredibly high resolution for its pixel count, equivalent to what I would expect from a 5-megapixel digital SLR model. This conclusion is subjective to some extent, but is
based on a close examination of large prints generated from technically excellent SD10 images made at ISO 100.

After upscaling the 9.8MB image files to 29.9MB in Photoshop, I was able to make 11x16.5" outputs that are razor sharp and richly detailed, exhibiting the quality that I expect from Superfine/Large JPEG images made with a 6-megapixel digital SLR.

I also experimented with making large prints from the 4536x3024 pixel image files--originally "doubled" with interpolation in the Photo Pro software. They look great from a distance, but on closer scrutiny, they're not quite as sharp and do not exhibit higher resolution. Surprisingly, Re-sampling (with bicubic interpolation) in Photoshop CS appears to be more effective than interpolation in the Photo Pro software.

Taking the testing to the limit, I decided to upscale a technically superb SD10 image to the 36MB required for a 12x18" output at 240 ppi. The resulting print is surprisingly good though a bit "soft" and exhibiting lower resolution of intricate detail. Still, friends who examined the framed print--from a typical viewing distance of 6 ft--offered higher ratings, ranging from "beautiful" to "excellent." That's an impressive achievement for the Sigma SD10 when you consider the 2268x1512 pixel count in the original 9.8MB file.

Final Evaluation
Because this camera requires Sigma SA-mount lenses and a dedicated DG SA-N flash unit, it will primarily appeal to those who do not already own a full system of some other brand. The SD10 will particularly satisfy photographers who generally work at ISO 100 or 200, do not need "extra" features or maximum speed for action photography, and would be happy with 11x16.5" ink jet prints suitable for framing.
If you fall into that category and if you appreciate the benefits of raw capture, check out the SD10. Try its various conventional and digital features to shoot and play back a few dozen frames. Within 10 minutes, you should know whether this camera will meet your shooting needs. Add some of the fine Sigma lenses and a flash unit, and you'll be well on your way to serious image-making.

The new Photo Pro (Version 2.0) software offers numerous controls for enhancing raw format files before converting them into 8-bit or 16-bit JPEG or TIFF format in the desired color space. One of the most versatile converter programs bundled with any digital camera, Photo Pro is very fast and intuitive in its operation.

Unique Foveon X3 Technology: The "Megasensor" Debate
The Sigma SD10 employs a unique Foveon CMOS X3 "full color" sensor that generates raw data that must be converted using the special Photo Pro software. The term X3 refers to the three layers of "color photodetectors" designed to record all three primary colors of light--red, green, and blue--at every pixel. (By contrast, a conventional "Bayer-mosaic" sensor uses a single layer of photodetectors; every third pixel senses either red, green, or blue.) Consequently, an X3 sensor does not require the color-interpolation processing or the artifact-reducing blur filters used in other cameras and should produce images with very high sharpness and great color purity without color artifacts, such as moiré (a distortion pattern).

Whether the SD10 is a 3.43-megapixel or 10.29-megapixel camera is still open to debate. Foveon literature refers to the photodetectors as pixels and labels the X3 as a "10-Megasensor" chip designed to provide resolution and sharpness "competitive with 6-Megasensor Bayer-mosaic image sensors." In practical terms, the image resolution in "Hi" mode is 2268x1512 pixels and the file size--after conversion to TIFF, in 8-bit color--is approximately 9.8MB. That's not a very large file, but the excellent image quality allowed me to make large prints suitable for framing, as discussed in the text.

While the earlier SD9 camera also incorporated a Foveon X3 sensor, the SD10 benefits from an enhanced version. Although similar in many respects, the current X3 Pro sensor boasts wider dynamic range for more detail in highlights as well as less digital noise at high ISO and in long exposures. In order to maximize image quality, the SD10 is bundled with an upgraded version (2.0) of the Photo Pro software (from Foveon). Faster and more versatile than the original version, this converter offers even more options for correcting various image parameters, useful for enhancing the raw data files before conversion to TIFF format.

Technical Specifications
Sensor: 20.7x13.8mm Foveon CMOS X3 Pro sensor; 10.3 million photodetectors; 3.43 million recording pixels
Lens Mount: Sigma autofocus mount; accepts SA-mount lenses
Actual Field Of View: 1.7x focal length magnifier
Capture Formats: Raw format only, 12 bit, with lossless compression; high (2268x1512), medium (1512x1008), and low (1134x756) resolution options
Capture Modes: Single-shot and continuous framing at 1.9 fps for up to six frames in high-res capture, 2.4 fps for up to 14 frames in medium res, and 2.5 fps for up to 30 frames in low-resolution capture options
Operating Modes: Program AE with shift; Aperture and Shutter Priority AE; Manual
Exposure Control: Eight-segment Evaluative, Center-Weighted, and heavily Center-Weighted metering; AE Lock; Exposure Compensation and Bracketing in 0.3 EV steps
Shutter Speed Range: 1/6000 to 15 sec plus Bulb
White Balance: Auto and Custom; also, Sunlight, Shade, Overcast, Incandescent, Fluorescent, and Flash options
Focusing: TTL phase detection autofocus with Single and Continuous predictive autofocus; single-point sensor
Sensitivity: ISO 100, 200, 400, and 800 plus Extended Mode ISO 1600
Other Features: Diopter correction eyepiece; 1.8" LCD monitor; hot shoe for external flash; reflex mirror pre-lock; depth of field preview; histogram and magnification available in Playback; LCD Brightness and Contrast adjustment; Photo Pro raw converter software with numerous Automatic and user-selectable correction options
Connectivity: IEEE1394 FireWire, USB 1.1, and Video Out
Storage: CompactFlash Type I and II; Microdrive
Power: Four AA or two CR-V3 lithium batteries; AC adapter (included); optional Power Pack SD accepts eight AA or four CR-V3 batteries
Dimensions/Weight: 5.9x4.7x3.1"; 27.7 oz
Street Price: $1349

For more information on the SD10, visit Sigma's website at: www.sigma-photo.com.

Peter K. Burian, a free-lancer stock photographer and long-time "Shutterbug" and "eDigitalPHOTO" contributor, is the author of a new book, "Mastering Digital Photography and Imaging" (Sybex, March 2004). Covering all aspects of the topic--the technology, equipment, and techniques--this book provides 300 pages of practical advice for photo enthusiasts.

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