Panasonic FP1 has a
12.0MP 1/2.3-inch (6.08 x 4.56 mm ) sized CCD sensor and features Venus Engine IV processor. On the other hand, Panasonic FP3 has a
14.0MP 1/2.3-inch (6.08 x 4.56 mm ) sized CCD sensor and features Venus Engine IV processor.
Below you can see the FP1 and FP3 sensor size comparison.
Panasonic FP1 and Panasonic FP3 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 Panasonic FP1 has 16% larger pixel area compared to Panasonic FP3, it has potential to collect more light on pixel level hence have less noise in low light / High ISO images.