Panasonic FS12 has a
12.0MP 1/2.3-inch (6.08 x 4.56 mm ) sized CCD sensor . On the other hand, FujiFilm S4000 has a
14.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor .
Below you can see the FS12 and S4000 sensor size comparison.
Sensor Size and Resolution Comparison image of Panasonic FS12 and FujiFilm S4000 Cameras
Panasonic FS12 and FujiFilm S4000 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
Panasonic FS12
or the
FujiFilm S4000 ,
including hyperfocal distance.