Sigma BF has a
24.6MP Full frame (36 x 24 mm ) sized CMOS sensor . On the other hand, Nikon Z5 II has a
25.0MP Full frame (35.9 x 23.9 mm ) sized BSI-CMOS sensor and features Expeed 7 processor.
Another difference between these two cameras is that Sigma BF's sensor lacks anti-alias (Low-Pass) filter. 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 BF and Z5 II sensor size comparison.
Sensor Size and Resolution Comparison image of Sigma BF and Nikon Z5 II Cameras
Sigma BF and Nikon Z5 II have almost the same sensor size, so neither of them has any significant advantage over the other in terms of providing control over depth of field when used with the 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
Sigma BF
or the
Nikon Z5 II ,
including hyperfocal distance.