Panasonic ZS3 has a
10.0MP 1/2.3-inch (6.08 x 4.56 mm ) sized CCD sensor . On the other hand, Pentax H90 has a
12.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor and features Prime processor.
Below you can see the ZS3 and H90 sensor size comparison.
Panasonic ZS3 and Pentax H90 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.