Both Canon S95 and Olympus E-420 have 10.0 MP resolution sensors but Canon S95's sensor is 1/1.7-inch (7.44 x 5.58 mm ) and Olympus E-420's sensor is Four Thirds (17.3 x 13 mm ).
Since Olympus E-420'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 Canon S95.
Below you can see the S95 and E-420 sensor size comparison.
Sensor Size and Resolution Comparison image of Canon S95 and Olympus E-420 Cameras
As seen above, Olympus E-420 has a 5.4x Larger sensor area than Canon S95. 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. Canon S95 and Olympus E-420 sensors have been tested by DxO and the results show that E-420 has a better overall score of 56, 9 points higher compared to S95's score of 47.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Canon S95
47
20.4 bits
11.3 Evs
153 ISO
Olympus E-420
56
21.5 bits
10.4 Evs
527 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
Canon S95
or the
Olympus E-420 ,
including hyperfocal distance.
One thing to watch when comparing these two: they have different sensor sizes
(1/1.7-inch 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.
