FujiFilm JX300 has a
14.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor . On the other hand, Fujifilm JX550 has a
16.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor .
Below you can see the JX300 and JX550 sensor size comparison.
Sensor Size and Resolution Comparison image of FujiFilm JX300 and Fujifilm JX550 Cameras
FujiFilm JX300 and Fujifilm JX550 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 FujiFilm JX300 has 7% larger pixel area compared to Fujifilm JX550, 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
FujiFilm JX300
or the
Fujifilm JX550 ,
including hyperfocal distance.