Most photographers know Sigma as a lens manufacturer, but the company also makes cameras, including a line of DSLRs that began in 2002 with the SD9. The new SD15, like its SD9, SD10 and SD14 predecessors, stands out for its unique Foveon image sensor and straightforward, no-nonsense design concept.
Unlike the sensors used in all other DSLRs, the Foveon records all three primary colors at every pixel site. This eliminates the need for a Bayer-array filter grid over the pixels, an image-softening, low-pass filter to minimize the resulting artifacts, and the complex demosaicing algorithms that interpolate the missing colors at each pixel site by using information from neighboring pixels. The result is images with detail beyond their horizontal-by-vertical pixel count, and natural-looking fine details—especially nice when photographing bird feathers and foliage. Sigma purchased Foveon in 2008 and so is likely to continue to be the only brand offering the X3 sensor.
Convenient Mode Dial
Some of the bells-and-whistles DSLRs require locating and pressing a button while rotating a dial to set the desired exposure mode. With the SD15, just rotate the mode dial to P(rogram AE), A(perture-priority AE), S(hutter-priority AE) or M(anual), and you’re there.
Fill-flash is an important outdoor tool. The SD15 has a built-in, pop-up flash unit; and two shoe-mount accessory units are available—one with wireless, off-camera capability.
Again, selecting a drive mode or locking the mirror up for a shot can be a tad complex with many DSLRs. With the SD15, just rotate the drive dial to single-shot, continuous, mirror up, etc.
There’s no sensor-shake dust remover as found in other DSLRs, but the SD15 features a dust protector that can be removed for easy cleaning—and infrared photography.
Foveon X3 Sensor
The Foveon X3 Direct Image Sensor records all three primary colors at every pixel site, yielding images with fine detail beyond their horizontal-by-vertical pixel count—perfect for photographing bird feathers and foliage