Sony A6400 has a
24.0MP APS-C (23.5 x 15.6 mm ) sized CMOS sensor and features Bionz X processor. On the other hand, Samsung NX1 has a
28.0MP APS-C (23.5 x 15.7 mm ) sized BSI-CMOS sensor and features DRIMe 5 processor.
One other difference between these two cameras that is worth mentioning is that Samsung NX1's sensor doesn't have an 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 A6400 and NX1 sensor size comparison.
Sensor Size and Resolution Comparison image of Sony A6400 and Samsung NX1 Cameras
Sony A6400 and Samsung NX1 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.
DxOMark Sensor Scores
At Camera Decision, we also look at Dxo Mark sensors when available as we think it is a good indicator of image quality.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Sony A6400
83
24.0 bits
13.6 Evs
1431 ISO
Samsung NX1
83
24.2 bits
13.2 Evs
1363 ISO
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
Sony A6400
or the
Samsung NX1 ,
including hyperfocal distance.