Olympus E-520 has a
10.0MP Four Thirds (17.3 x 13 mm ) sized CMOS sensor . On the other hand, Pentax K-3 has a
24.0MP APS-C (23.5 x 15.6 mm ) sized CMOS sensor and features Prime III processor.
Pentax K-3's sensor provides 14MP more than Olympus E-520's sensor, which gives a significant advantage in real life. You can print your images larger or crop more freely.
On the other hand, please keep in mind that Max sensor resolution is not the only determinant of resolving power. Factors such as the optical elements, low pass filter, pixel size and sensor technology also affects the final resolution of the captured image.
One other difference between these two cameras that is worth mentioning is that Pentax K-3's sensor doesn't have an anti-alias (Low-Pass) filter. Removing anti-alias filter increases the sharpness and level of detail but at the same time, it increases the chance of moiré occurring in certain scenes.
Below you can see the E-520 and K-3 sensor size comparison.
Sensor Size and Resolution Comparison image of Olympus E-520 and Pentax K-3 Cameras
As seen above, Pentax K-3 has a 1.6x Larger sensor area than Olympus E-520. 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-520 and Pentax K-3 sensors have been tested by DxO and the results show that K-3 has a better overall score of 80, 25 points higher compared to E-520's score of 55.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Olympus E-520
55
21.4 bits
10.4 Evs
548 ISO
Pentax K-3
80
23.7 bits
13.4 Evs
1216 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-520
or the
Pentax K-3 ,
including hyperfocal distance.
One thing to watch when comparing these two: they have different sensor sizes
(Four Thirds 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.
