Casio EX-Z90 has a
12.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor and features Digic 4 processor. On the other hand, Kodak Z981 has a
14.0MP 1/2.3-inch (6.08 x 4.56 mm ) sized CCD sensor .
Below you can see the EX-Z90 and Z981 sensor size comparison.
Sensor Size and Resolution Comparison image of Casio EX-Z90 and Kodak Z981 Cameras
Casio EX-Z90 and Kodak Z981 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
Casio EX-Z90
or the
Kodak Z981 ,
including hyperfocal distance.