Both Olympus E-PL5 and Nikon D4s have 16.0 MP resolution sensors but Olympus E-PL5's sensor is Four Thirds (17.3 x 13 mm ) and Nikon D4s's sensor is Full frame (36 x 23.9 mm ).
Since Nikon D4s'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 Olympus E-PL5.
Below you can see the E-PL5 and D4s sensor size comparison.
Sensor Size and Resolution Comparison image of Olympus E-PL5 and Nikon D4s Cameras
As seen above, Nikon D4s has a 3.8x Larger sensor area than Olympus E-PL5. 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. Olympus E-PL5 and Nikon D4s sensors have been tested by DxO and the results show that D4s has a better overall score of 89, 17 points higher compared to E-PL5's score of 72.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Olympus E-PL5
72
22.8 bits
12.3 Evs
889 ISO
Nikon D4s
89
24.4 bits
13.3 Evs
3074 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
Olympus E-PL5
or the
Nikon D4s ,
including hyperfocal distance.
One thing to watch when comparing these two: they have different sensor sizes
(Four Thirds versus Full frame),
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.
