Panasonic ZR3 has a
14.0MP 1/2.3-inch (6.08 x 4.56 mm ) sized CCD sensor and features Venus Engine HD II processor. On the other hand, Panasonic ZS15 has a
12.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CMOS sensor .
Below you can see the ZR3 and ZS15 sensor size comparison.
Sensor Size and Resolution Comparison image of Panasonic ZR3 and Panasonic ZS15 Cameras
Panasonic ZR3 and Panasonic ZS15 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 ZR3
or the
Panasonic ZS15 ,
including hyperfocal distance.