Casio EX-Z800 has a
14.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor and features Exilim Engine 5.0 processor. On the other hand, Olympus Tough-3000 has a
12.0MP 1/2.3-inch (6.08 x 4.56 mm ) sized CCD sensor and features TruePic III processor.
Below you can see the EX-Z800 and Tough-3000 sensor size comparison.
Casio EX-Z800 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.