Sigma DP1 Merrill has a APS-C sensor with dimensions of 24 x 16 mm and sensor area of 384.00mm2.
Sigma DP1 Merrill's sensor is 15% larger than the average Large Sensor Compact sensor in its class. In cases where all the other parameters are the same between two cameras, the one with the larger sensor collects more light per pixel and performs better (less noise) in low light / High ISO conditions . Larger sensors also give the photographer more control on the depth of field.
Read our detailed Sigma DP1 Merrill Review