Both Canon SX120 IS and Canon G12 have 10.0 MP resolution sensors but Canon SX120 IS's sensor is 1/2.5-inch (5.744 x 4.308 mm ) and Canon G12's sensor is 1/1.7-inch (7.44 x 5.58 mm ).
Since Canon G12'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 Canon SX120 IS.
Below you can see the SX120 IS and G12 sensor size comparison.
Sensor Size and Resolution Comparison image of Canon SX120 IS and Canon G12 Cameras
As seen above, Canon G12 has a 1.7x Larger sensor area than Canon SX120 IS. 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
Canon SX120 IS
or the
Canon G12 ,
including hyperfocal distance.
One thing to watch when comparing these two: they have different sensor sizes
(1/2.5-inch versus 1/1.7-inch),
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.
