Both Pentax E70 and Sony A330 have 10.0 MP resolution sensors but Pentax E70's sensor is 1/2.3-inch (6.08 x 4.56 mm ) and Sony A330's sensor is APS-C (23.5 x 15.7 mm ).
Since Sony A330'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 Pentax E70.
Below you can see the E70 and A330 sensor size comparison.
Sensor Size and Resolution Comparison image of Pentax E70 and Sony A330 Cameras
As seen above, Sony A330 has a 13.3x Larger sensor area than Pentax E70. 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
Pentax E70
or the
Sony A330 ,
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.
