Sigma SD Quattro Digital Camera with APS-C Sensor

Foveon Direct Image Sensor The World’s Only Image Capture System To Use Vertical Color Separation Technology

Starting with our very first digital camera, we have featured the Foveon direct image sensor, which offers radically better image quality than any other sensor available. Leveraging the light absorption characteristics of silicon, the sensor comprises three layers of photodiodes, each at a different depth within the silicon and each corresponding to a different RGB color. Since it is the only sensor to use this superior vertical color separation technology, it is also the world’s only direct image sensor.

Almost all other image sensors are mosaic sensors, which use an array of RGB color filters in a single horizontal plane to capture color information. Each pixel is assigned only one of the three colors and cannot capture all three colors at once. In contrast, the Foveon direct image sensor captures color vertically, recording hue, value, and chroma accurately and completely for each pixel.

In the Foveon direct image sensor, there are no color filters which would cause a loss of information transmitted by light. Moreover, there is no low-pass filter needed to correct the interference caused by a color filter array. Finally, unlike the data from other sensors, which requires artificial interpolation to “fill in” missing colors, the data from the Foveon direct image sensor is complete for every single pixel and requires no interpolation. The unique technological principle of this sensor produces consistently outstanding image quality.

Combination of two AF detection methods

Phase detection AF is superior for speed performance, while contract detection AF is superior for focusing accuracy. Combining these two methods in a single system delivers AF that is fast and precise at the same time. In addition, this approach to autofocus takes full advantage of the characteristics of high-performance lenses. The Single AF mode is optimal for everyday photography, while the Continuous AF mode is optimal for focusing on a moving object. In the latter mode, pressing the shutter button halfway causes autofocus to operate continuously, while Movement Prediction AF operates at the same time for more accurate autofocusing. A variety of other AF modes are also available. 9-Point Selection AF mode allows the user to select among nine focus frames. Free Movement AF mode allows the user to select the focus frame with high precision. Face Detection AF mode detects human faces and prioritizes focusing on them. The AF assist light incorporated in the camera body makes possible the use of AF even in low-light conditions.