Olympus SP-565UZ has a
10.0MP 1/2.3-inch (6.08 x 4.56 mm ) sized CCD sensor . On the other hand, Canon A3100 IS has a
12.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor .
Below you can see the SP-565UZ and A3100 IS sensor size comparison.
Sensor Size and Resolution Comparison image of Olympus SP-565UZ and Canon A3100 IS Cameras
Olympus SP-565UZ and Canon A3100 IS 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
Olympus SP-565UZ
or the
Canon A3100 IS ,
including hyperfocal distance.