Sigma has announced the availability of the mirrorless sd Four in the US market. This model uses the latest version of the Foveon X3 sensors. The peculiarity of this solution consists in the structure with three layers: the first layer is the one that records the information at full resolution and is sensitive to the blue chromatic component. The other two layers, however, record information to 1/4 of the resolution and are sensitive to green and red components. The sensor is APS-C format (the one used on previous Sigma Four). The top layer provides a resolution of 19.6 megapixels, while the lower layers amounted to about 4.9 megapixels. Sigma likens the level of detail to that of a Bayer sensor with 39 megapixels.
The body of the mirrorless is made of magnesium alloy and is resistant to dust and moisture. The autofocus will offer a dual mode, combining the phase detection (that favors speed in pursuit of the subjects) and the contrast detection (which favors accuracy). Will also be the settings in “Movement Prediction”, “Face Detection”, “Free Movement” and “Focus Peaking”.