Sony H50 has a
9.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor . On the other hand, Canon SD940 IS has a
12.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor and features Digic 4 processor.
Below you can see the H50 and SD940 IS sensor size comparison.
Sony H50 and Canon SD940 IS 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 H50 has 33% larger pixel area compared to Canon SD940 IS, it has potential to collect more light on pixel level hence have less noise in low light / High ISO images.