Canon SX270 HS has a
12.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized BSI-CMOS sensor and features Digic 6 processor. On the other hand, Panasonic ZS8 has a
14.0MP 1/2.3-inch (6.08 x 4.56 mm ) sized CCD sensor and features Venus Engine FHD processor.
Below you can see the SX270 HS and ZS8 sensor size comparison.
Canon SX270 HS and Panasonic ZS8 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.