Sony A7 III has a
24.0MP Full frame (35.8 x 23.8 mm ) sized BSI-CMOS sensor and features Bionz X processor. On the other hand, Leica M9-P has a
18.0MP Full frame (36 x 24 mm ) sized CCD sensor .
Sony A7 III's sensor provides 6MP more than Leica M9-P'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.
One other difference between these two cameras that is worth mentioning is that Leica M9-P'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 A7 III and M9-P sensor size comparison.
Sensor Size and Resolution Comparison image of Sony A7 III and Leica M9-P Cameras
Sony A7 III and Leica M9-P 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
Both Sony A7 III and Leica M9-P sensors have been tested by DxoMark. DxoMark scores camera sensors for color depth (DXO Portrait), dynamic range (DXO Landscape) and low-light sensitivity (DXO Sports), and also gives them an overall score. Of the two cameras that we are comparing, A7 III has scored 96, 28 points higher than M9-P.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Sony A7 III
96
25.0 bits
14.7 Evs
3730 ISO
Leica M9-P
68
22.5 bits
11.6 Evs
854 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 A7 III
or the
Leica M9-P ,
including hyperfocal distance.
