Both Sony RX100 and Sony RX100 III have 20.0 MP resolution sensors but Sony RX100's sensor is 1-inch (13.2 x 8.8 mm ) and Sony RX100 III's sensor is 1″ (13.2 x 8.8 mm ).
Since Sony RX100 III'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 RX100.
Below you can see the RX100 and RX100 III sensor size comparison.
Sensor Size and Resolution Comparison image of Sony RX100 and Sony RX100 III Cameras
Sony RX100 and Sony RX100 III 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.
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 RX100 and Sony RX100 III sensors have been tested by DxO and the results show that RX100 III has a better overall score of 67, 1 points higher compared to RX100's score of 66.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Sony RX100
66
22.6 bits
12.4 Evs
390 ISO
Sony RX100 III
67
22.4 bits
12.3 Evs
495 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 RX100
or the
Sony RX100 III ,
including hyperfocal distance.
One thing to watch when comparing these two: they have different sensor sizes
(1-inch versus 1″ ),
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.
