Both Sony W570 and Sony A57 have 16.0 MP resolution sensors but Sony W570's sensor is 1/2.3-inch (6.17 x 4.55 mm ) and Sony A57's sensor is APS-C (23.5 x 15.6 mm ).
Since Sony A57'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 Sony W570.
Below you can see the W570 and A57 sensor size comparison.
Sensor Size and Resolution Comparison image of Sony W570 and Sony A57 Cameras
As seen above, Sony A57 has a 13.1x Larger sensor area than Sony W570. 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
Sony W570
or the
Sony A57 ,
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.
