Panasonic S9 has a
24.0MP Full frame (35.6 x 23.8 mm ) sized CMOS sensor and features Venus Engine processor. On the other hand, Sigma BF has a
24.6MP Full frame (36 x 24 mm ) sized CMOS sensor .
Another similarity between these two cameras is that both Sigma BF and Panasonic S9 sensors lack anti-alias (Low-Pass) filters. Removing anti-alias filter increases the sharpness and level of detail but at the same time, it increases the chance of moiré occurring in certain scenes.
Below you can see the S9 and BF sensor size comparison.
Sensor Size and Resolution Comparison image of Panasonic S9 and Sigma BF Cameras
Panasonic S9 and Sigma BF have the same sensor sizes so they will provide same level of control over the depth of field when used with same focal length and aperture.
Sensor size sets the circle of confusion, so it drives how much depth of field each
of these bodies gives you at a given aperture. You can calculate it exactly for the
Panasonic S9
or the
Sigma BF ,
including hyperfocal distance.