Both Sony RX10 III and Sony a5000 have 20.0 MP resolution sensors but Sony RX10 III's sensor is 1″ (13.2 x 8.8 mm ) and Sony a5000's sensor is APS-C (23.2 x 15.4 mm ).
Since Sony a5000's has a larger sensor area with the same resolution, this means that it also has a larger pixel area hence better light collecting capacity for a given aperture compared to Sony RX10 III.
Below you can see the RX10 III and a5000 sensor size comparison.
Sensor Size and Resolution Comparison image of Sony RX10 III and Sony a5000 Cameras
As seen above, Sony a5000 has a 3.1x Larger sensor area than Sony RX10 III. Larger sensors give photographer more control on the depth of field and blurry background compared to smaller sensor when shot in same focal length and aperture.
DxOMark Sensor Scores
DxOMark is a benchmark that scientifically assesses image quality of camera sensors. It 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. Sony RX10 III and Sony a5000 sensors have been tested by DxO and the results show that a5000 has a better overall score of 79, 9 points higher compared to RX10 III's score of 70.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Sony RX10 III
70
23.1 bits
12.6 Evs
472 ISO
Sony a5000
79
23.8 bits
13.0 Evs
1089 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 RX10 III
or the
Sony a5000 ,
including hyperfocal distance.
One thing to watch when comparing these two: they have different sensor sizes
(1″ versus APS-C),
so compare them at the same framing rather than the same focal length.
Put the same focal length on the smaller sensor and it will show less depth of
field, not more, because it also crops tighter. The calculator shows the
full frame equivalent focal length for each body so you can match the framing.
