Panasonic ZS40 has a
18.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CMOS sensor and features Venus Engine processor. On the other hand, Olympus SP-620 UZ has a
16.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor and features TruePic III+ processor.
Below you can see the ZS40 and SP-620 UZ sensor size comparison.
Sensor Size and Resolution Comparison image of Panasonic ZS40 and Olympus SP-620 UZ Cameras
Panasonic ZS40 and Olympus SP-620 UZ have the same sensor sizes so they will provide same level of control over the depth of field when used with 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
Panasonic ZS40
or the
Olympus SP-620 UZ ,
including hyperfocal distance.