Sigma SD Quattro Digital Camera with 30mm F1.4 DC HSM It features the Sigma SA mount and is designed to take full advantage of Sigma Global Vision lens. Superb optical performance. There are two AF detection methods in this camera, and by combing these two into one single system, fast and precise AF is achieved. There are two AF detection methods in this camera, and by combing these tow into one single system, fast and precise AF is achieved. SD Quattro is a high resolution camera ( precaution: Dust that gets on the sensor will be visible in photos. It is important to be careful when replacing/removing a lens to prevent dust from getting on the sensor)