Blackmagic Cinema 6K has a
24.0MP Full frame (36 x 24 mm ) sized CMOS sensor . On the other hand, Sony FX6 has a
10.9MP Full frame (36 x 24 mm ) sized CMOS sensor .
Blackmagic Cinema 6K's sensor provides 13.1MP more than Sony FX6's sensor, which gives a significant advantage in real life. You can print your images larger or crop more freely.
On the other hand, please keep in mind that Max sensor resolution is not the only determinant of resolving power. Factors such as the optical elements, low pass filter, pixel size and sensor technology also affects the final resolution of the captured image.
Below you can see the Cinema Camera 6K and FX6 sensor size comparison.
Sensor Size and Resolution Comparison image of Blackmagic Cinema 6K and Sony FX6 Cameras
Blackmagic Cinema 6K and Sony FX6 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. On the other hand, since Sony FX6 has 82% larger pixel area (64.00µm 2 vs 35.00µm 2 ) compared to Blackmagic Cinema 6K, it has larger pixel area to collect light hence potential to have less noise in low light / High ISO images.
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
Blackmagic Cinema 6K
or the
Sony FX6 ,
including hyperfocal distance.