Nikon S3000 has a
12.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor and features Expeed C2 processor. On the other hand, Casio EX-ZR300 has a
16.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized BSI-CMOS sensor and features Exilim Engine HS processor.
Below you can see the S3000 and EX-ZR300 sensor size comparison.
Sensor Size and Resolution Comparison image of Nikon S3000 and Casio EX-ZR300 Cameras
Nikon S3000 and Casio EX-ZR300 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. On the other hand, since Nikon S3000 has 32% larger pixel area compared to Casio EX-ZR300, it has potential to collect more light on pixel level hence have less noise in low light / High ISO images.
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
Nikon S3000
or the
Casio EX-ZR300 ,
including hyperfocal distance.