Kodak Z915 has a
10.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor . On the other hand, Kodak Z950 has a
12.0MP 1/2.3-inch (6.08 x 4.56 mm ) sized CCD sensor .
Below you can see the Z915 and Z950 sensor size comparison.
Kodak Z915 and Kodak Z950 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.