Both Panasonic S2 and Sony A550 have 14.0 MP resolution sensors but Panasonic S2's sensor is 1/2.3-inch (6.08 x 4.56 mm ) and Sony A550's sensor is APS-C (23.4 x 15.6 mm ).
Since Sony A550'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 Panasonic S2.
Below you can see the S2 and A550 sensor size comparison.
Sensor Size and Resolution Comparison image of Panasonic S2 and Sony A550 Cameras
As seen above, Sony A550 has a 13.2x Larger sensor area than Panasonic S2. 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
Panasonic S2
or the
Sony A550 ,
including hyperfocal distance.
One thing to watch when comparing these two: they have different sensor sizes
(1/2.3-inch 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.
