Panasonic ZS40 has a
18.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CMOS sensor and features Venus Engine processor. On the other hand, Sony T99 has a
14.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor and features Bionz processor.
Below you can see the ZS40 and T99 sensor size comparison.
Panasonic ZS40 and Sony T99 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 T99 has 28% larger pixel area (2.01µm2 vs 1.56µm2) compared to Panasonic ZS40, it has larger pixel area to collect light hence potential to have less noise in low light / High ISO images.