Panasonic FX90 has a
12.0MP 1/2.3-inch (6.08 x 4.56 mm ) sized CCD sensor . On the other hand, Samsung HZ50W has a
14.0MP 1/2.3-inch (6.08 x 4.56 mm ) sized CCD sensor .
Below you can see the FX90 and HZ50W sensor size comparison.
Panasonic FX90 and Samsung HZ50W 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 Panasonic FX90 has 16% larger pixel area compared to Samsung HZ50W, it has potential to collect more light on pixel level hence have less noise in low light / High ISO images.