Casio EX-Z450 has a
12.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor . On the other hand, Samsung ST600 has a
14.0MP 1/2.3-inch (6.08 x 4.56 mm ) sized CCD sensor .
Below you can see the EX-Z450 and ST600 sensor size comparison.
Casio EX-Z450 and Samsung ST600 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.