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Monday, September 1, 2008

Does Your Camera Have An Evil Twin?

What’s in a camera’s DNA? We’ll show you the features and technologies that have trickled down from the top-end models to the popular sweet-spot cameras.

This Article Features Photo Zoom

Sigma SD14 & DP1
These cameras are twins in that they use the same unique Foveon X3 image sensor. The SD14 is a D-SLR; the DP1 is a compact, all-in-one digital camera with a huge sensor compared to its competitors and a built-in 16.6mm lens (equivalent to a 28mm lens on a 35mm camera with the image sensor’s 1.7x focal-length factor).

The DP1 features a new Three-layer Responsive Ultimate Engine (TRUE) image-processing engine developed specifically for the DP1’s sensor; the SD14 has a previous-generation imaging engine also designed for the Foveon sensor.

While other imaging sensors record just one primary color at each pixel site, producing data for the other colors by interpolating data from neighboring pixels via complex proprietary algorithms, the Foveon X3 sensor used in the SD14 and DP1 records all three primary colors at every pixel site, functioning much like color film. The Foveon sensor takes advantage of the fact that different light wavelengths penetrate silicon to different depths: red the deepest, green a bit less and blue least of all. Thus, three pixel layers are stacked, the top recording blue light, the middle one green and the bottom one red. The advantages? Every pixel site records every color, so no colored filter array is needed over the pixels, no interpolation of missing colors is needed and no image-softening, anti-aliasing filter is needed.

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Sigma SD14
The Sigma SD14 is well known for its use of the Foveon X3 image sensor. The Foveon technology captures all color data on each pixel. The sensor has 4.7 million pixels, but since all color data is captured in each pixel, Sigma prefers to refer to it as a 14-megapixel sensor.

Sigma DP1
Unlike most of the cameras in this article, the DP1’s primary inheritance from the SD14 is the Foveon X3 sensor. The fixed, non-zoom lens is attached to a solid body, making it an interesting second camera for many shooters.

Bottom Line: As a D-SLR, the SD14 is the more versatile “twin,” providing TTL viewing with a wide range of interchangeable lenses. The compact DP1 is a fine “take-anywhere” camera that fits in a large pocket. Both have the same Foveon X3 sensor.

Sigma SD14 Sigma DP1
Sensor: 4.7x3-megapixel Foveon X3
4.7x3-megapixel Foveon X3
Sensor Size: 20.7x13.8mm (1.7x)
20.7x13.8mm (1.7x)
Processor: Sigma
A/D Conversion: 12-bit 12-bit
Sensor Cleaning: No
AF Points: 5
Metering: 8-segment, CW, center-area
Evaluative, CW, spot
ISO Range: 100-1600
Shutter Speeds: 30 to 1⁄4000 sec., plus B
15 to 1⁄1000 sec., plus B
Max. Advance Rate: 3 fps 3 fps
Dimensions: 6.3x6.2x3.4 in.
4.5x2.3x2 in.
Weight: 43.7 oz.
8.8 oz.
Estimated Street Price: $850


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