Panasonic ZS35 has a
16.0MP 1/2.3-inch (6.08 x 4.56 mm ) sized CMOS sensor . On the other hand, Nikon S640 has a
12.0MP 1/2.3-inch (6.08 x 4.56 mm ) sized CCD sensor and features Expeed processor.
Below you can see the ZS35 and S640 sensor size comparison.
Sensor Size and Resolution Comparison image of Panasonic ZS35 and Nikon S640 Cameras
Panasonic ZS35 and Nikon S640 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 S640 has 32% larger pixel area (2.31µm 2 vs 1.74µm 2 ) compared to Panasonic ZS35, it has larger pixel area to collect light hence potential to 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
Panasonic ZS35
or the
Nikon S640 ,
including hyperfocal distance.