Both Canon 450D and Olympus E-PL1 have 12.0 MP resolution sensors but Canon 450D's sensor is APS-C (22.2 x 14.8 mm ) and Olympus E-PL1's sensor is Four Thirds (17.3 x 13 mm ).
Since Canon 450D'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-PL1.
Below you can see the 450D and E-PL1 sensor size comparison.
Sensor Size and Resolution Comparison image of Canon 450D and Olympus E-PL1 Cameras
As seen above, Canon 450D has a 1.5x Larger sensor area than Olympus E-PL1. 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
Both Canon 450D and Olympus E-PL1 sensors have been tested by DxoMark. DxoMark 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. Of the two cameras that we are comparing, 450D has scored 61, 7 points higher than E-PL1.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Canon 450D
61
21.9 bits
10.8 Evs
692 ISO
Olympus E-PL1
54
21.5 bits
10.1 Evs
487 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 450D
or the
Olympus E-PL1 ,
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.
