Sigma SD9 has a 3.0MP APS-C (20.7 x 13.8 mm ) sized CMOS (Foveon X3) sensor . You can shoot at maximum resolution of 2268 x 1512 pixels with aspect ratios of and 3:2. SD9 has a native ISO range of 100 - 400 and it can save files in RAW format which gives you a wider room for post processing.
Sigma SD9 is not the highest resolution APS-C camera. Fujifilm X-E5 with its 40.0MP sensor is leading in this class. Check the comparison of Sigma SD9 vs Fujifilm X-E5 or take a look at Highest resolution DSLR cameras list.
Anti-Aliasing Filter
Another important feature about Sigma SD9's sensor is the lack of anti-alias (Low-pass) filter. Removing anti-aliasing filter increases the sharpness and level of detail but on the other side it also increases the chance of moiré occurring in certain scenes.
Let's look at how the size of the Sigma SD9's APS-C sensor compares with other standard sensor sizes.
Comparison image of Sigma SD9 Sensor Size with other standard sensors
Sensor size is what determines the circle of confusion, and therefore how much
depth of field Sigma SD9 gives you at any given aperture.
You can
calculate
the exact depth of field for the Sigma SD9
at any focal length, aperture and subject distance, including the hyperfocal distance
for landscapes and the very shallow focus zone you get with long telephoto lenses.
