Both Olympus 550WP and Canon 1D MIII have 10.0 MP resolution sensors but Olympus 550WP's sensor is 1/2.3-inch (6.08 x 4.56 mm ) and Canon 1D MIII's sensor is APS-H (28.7 x 18.7 mm ).
Since Canon 1D MIII'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 550WP.
Below you can see the 550WP and 1D MIII sensor size comparison.
Sensor Size and Resolution Comparison image of Olympus 550WP and Canon 1D MIII Cameras
As seen above, Canon 1D MIII has a 19.4x Larger sensor area than Olympus 550WP. 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.
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 550WP
or the
Canon 1D MIII ,
including hyperfocal distance.
One thing to watch when comparing these two: they have different sensor sizes
(1/2.3-inch versus APS-H),
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.
