Pentax Efina has a
14.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor . On the other hand, Sony TX66 has a
18.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized BSI-CMOS sensor and features BIONZ processor.
Below you can see the Efina and TX66 sensor size comparison.
Pentax Efina and Sony TX66 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 Pentax Efina has 30% larger pixel area compared to Sony TX66, it has potential to collect more light on pixel level hence have less noise in low light / High ISO images.