Both Sony A58 and Panasonic GX8 have 20.0 MP resolution sensors but Sony A58's sensor is APS-C (23.2 x 15.4 m ) and Panasonic GX8's sensor is Four Thirds (17.3 x 13 mm ).
Since Sony A58'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 Panasonic GX8.
Below you can see the A58 and GX8 sensor size comparison.
Sensor Size and Resolution Comparison image of Sony A58 and Panasonic GX8 Cameras
As seen above, Sony A58 has a 1.5x Larger sensor area than Panasonic GX8. 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 A58 and Panasonic GX8 sensors have been tested by DxO and the results show that GX8 has a better overall score of 75, 1 points higher compared to A58's score of 74.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Sony A58
74
23.3 bits
12.5 Evs
753 ISO
Panasonic GX8
75
23.5 bits
12.6 Evs
806 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 A58
or the
Panasonic GX8 ,
including hyperfocal distance.
One thing to watch when comparing these two: they have different sensor sizes
(APS-C versus Four Thirds),
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.
