The info screen also includes a three-color histogram, which shows the distribution of dark, medium and light tones (from left to right) in graph form. If you press the info button in zoomed-in mode, the histogram will show data for the zoomed-in section of the image. There's even a cancelable overexposure warning, which indicates highlight areas in which detail might be lost to overexposure via a solid red overlay. You can't adjust the image via the histogram as you can in Photoshop, but you can reshoot it on the spot if the histogram indicates a problem. A supplied video cable allows you to connect the camera to a TV or other video device, and view the images big (but not terribly sharp—TV sets aren't high-res by computer-monitor standards).
A nice touch is the OK button shortcut: You can set the OK button to preform your most commonly used function at a touch (lock/unlock image, mark/unmark image, rotate image clockwise or counterclockwise, or toggle exposure warning on and off).
The SD9 gives you two easy ways to get your images out of the camera and into your computer. First, you can just connect the camera to the computer (both USB and IEEE 1394/FireWire cables are provided); second, you can take the CompactFlash card or Microdrive out of the camera and insert it into a computer-connected card reader. Either way, you need the supplied Sigma Photo Pro software to use the images, because they're recorded in a proprietary losslessly compressed RAW format that can't be read by Photoshop or other image-editing programs. To use the images, open the Photo Pro program, select the source folder (where you downloaded your RAW images), then select the format to which you'd like to convert the RAW images (JPEG, TIFF, etc.) and click the button. (It took 13-34 minutes to download and convert a full 512MB CompactFlash card's worth of images using various Windows PCs and Power Macs.)
You can choose among three recording resolution settings: HI (2268x1512 pixels), MED (1512x1008 pixels) and LOW (1134x756 pixels), with file sizes of approximately 8, 4 and 2 MB, respectively. All are recorded in the RAW 12-bit format. Our 512MB CompactFlash card thus held approximately 64 HI images, 128 MED images, or 256 LOW images (or any desired combination thereof—you can shoot any image at any resolution).
White balance is automatic, but you can also choose among six presets (sunlight, shade, overcast, incandescent, fluorescent and flash), or even set your own custom white balance.
Results
OK, so how do the images look?
Well, they are amazingly sharp and "fine grained" for the pixel count, and if you blow them up past 100% on-screen, they hold up better than conventional digital images of the same resolution (the pixels are barely visible at 200%). Color detail is excellent, and there are few "artifacts," as advertised. (The Foveon sensor is less vulnerable to moîre than conventional sensors, and thus there's no need for a sharpness-reducing blur filter to eliminate such artifacts.)
We'd suggest that you go to a camera store that sells the SD9 and check out sample images first-hand. Our images matched the ones provided by Sigma and Foveon in quality, so it should be safe to judge the store's example images against those made with competing digicams.
We reproduce images in Photographic at 300 dpi, and a 2268x1512-pixel image works out to 7.56x5.04 inches at 300 dpi, whether produced by a conventional CCD/CMOS sensor or by the Foveon X3 sensor. However, images from the SD9 do look sharper than similar-resolution images from conventional sensors when reproduced at any given size. And the 11x17-inch inkjet prints (133 dpi) we made from SD9 images looked great.
As mentioned, the process of downloading and converting the images before you can use them takes a while, but it's not that big a deal—it's simple to get underway, and then you can go do something else while your computer does its work. Once the images have been converted to JPEG or TIFF format, you use them just as you would any JPEG or TIFF images. The Photo Pro software lets you do a lots of image-adjusting before conversion (although the default auto mode works quite well)—click the Review Images button at the top right of the main window, then click the Adjustment Controls button at the top right of the Review Images window, and you gain access to controls to adjust exposure, contrast, shadow and highlight, saturation, sharpness and color, plus an adjustable histogram.
Because the SD9's 13.8x20.7mm image sensor is somewhat smaller than a full 35mm image frame, it "crops in" on the image formed by the lens by a factor of 1.7X: Put a 100mm lens on the SD9, and you get an image that shows the same area as one shot with a 170mm lens on a 35mm SLR. (Note: You don't get more magnification, just a tighter cropping of the image produced by the lens.) This is a little tough on wide-angle fanatics, because wide-angle lenses aren't as wide as they'd be on a 35mm camera. Sigma offers excellent SA-mount lenses (like the camera body, all the lenses have metal mounts and are made in Japan) with focal lengths from 14mm to 800mm, plus an 8mm circular fisheye and a 15mm full-frame fisheye. Thus, the SD9 user can shoot with the equivalent framing of 24mm to 1360mm (plus 13.6mm full-frame fisheye). This isn't great for superwide-angle acifionados, but certainly covers most shooting situations.
Actually, Sigma incorporates a nice "sports finder" feature that lets you see this effect. By retaining the full-frame viewfinder of the SA9 film camera, which shows considerably more than the area that will be recorded by the sensor, and grays out all but the live area, the SD9 lets you see an action subject as it enters the frame in the grayed-out peripheral area to help you prepare to shoot. Of course, you use the clear area in the center to frame the shot, as only that area will appear in the image. The clear area and grayed-out areas show how much "cropping" effect the smaller-than-35mm image sensor produces.
When we tested Sigma's SA9 film camera (July 2001 issue), we liked its performance, and thought it a very good value for its price. The same can be said for its SD9 digital "brother."
