Panasonic ZS1 has a 10.0MP 1/2.5-inch (5.744 x 4.308 mm ) sized CCD sensor . On the other hand, Nikon L19 has a 8.0MP 1/2.5-inch (5.744 x 4.308 mm ) sized CCD sensor .
Below you can see the ZS1 and L19 sensor size comparison.
Panasonic ZS1 and Nikon L19 have 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 L19 has 25% larger pixel area (3.10µm2 vs 2.48µm2) compared to Panasonic ZS1, it has larger pixel area to collect light hence potential to have less noise in low light / High ISO images.