Sony G3 has a
10.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor . On the other hand, Panasonic ZS7 has a
12.0MP 1/2.3-inch (6.08 x 4.56 mm ) sized CCD sensor and features Venus Engine HD II processor.
Below you can see the G3 and ZS7 sensor size comparison.
Sensor Size and Resolution Comparison image of Sony G3 and Panasonic ZS7 Cameras
Sony G3 and Panasonic ZS7 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
Sony G3
or the
Panasonic ZS7 ,
including hyperfocal distance.