The SD9 had two separate power systems; one set of CR-123A lithium batteries in the handgrip powered the camera functions, while another pair of CR-V3 batteries or four AA size rechargeables in a battery tray in the base powered the digital functions. This split power system showed that the camera functions (inherited from Sigma's SA-9 film SLR) were not integrated at all with the digital half.
Another unusual feature of the SD9 was its "dust cover" filter right behind the lens mount, to prevent dust getting into the chamber and onto the sensor when changing lenses.
Reviewers and users reported good results in good lighting, but poorer ones in low light using either high ISO sensitivity or longer exposures.
The SD9 was succeeded by an updated model, the SD10, which addressed the power and low-light issues.