Sony W510 has a
12.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor and features BIONZ processor. On the other hand, Ricoh PX has a
16.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor and features Smooth Imaging Engine IV processor.
Below you can see the W510 and PX sensor size comparison.
Sensor Size and Resolution Comparison image of Sony W510 and Ricoh PX Cameras
Sony W510 and Ricoh PX 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 Sony W510 has 18% larger pixel area compared to Ricoh PX, it has potential to collect more light on pixel level hence 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
Sony W510
or the
Ricoh PX ,
including hyperfocal distance.