Both Canon SD970 IS and Olympus Tough-3000 have 1/2.3-inch sized 12.0 MP resolution sensors so sensor size and resolution is not a differentiator between these two cameras.
Below you can see the SD970 IS and Tough-3000 sensor size comparison.
Sensor Size and Resolution Comparison image of Canon SD970 IS and Olympus Tough-3000 Cameras
Canon SD970 IS and Olympus Tough-3000 have almost the same sensor size, so neither of them has any significant advantage over the other in terms of providing control over depth of field when used with the 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 SD970 IS
or the
Olympus Tough-3000 ,
including hyperfocal distance.
