Nikon P500 has a
12.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized BSI-CMOS sensor and features Expeed C2 processor. On the other hand, Nikon L20 has a
10.0MP 1/2.3-inch (6.08 x 4.56 mm ) sized CCD sensor .
Below you can see the P500 and L20 sensor size comparison.
Sensor Size and Resolution Comparison image of Nikon P500 and Nikon L20 Cameras
Nikon P500 and Nikon L20 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
Nikon P500
or the
Nikon L20 ,
including hyperfocal distance.