I've recently switched over the Mac and the iMovie software. I've just shot a wedding video on a HDV Sony Z1 camera and imported the footage into iMovie 11 and edited together a few short sequences. The untuitive nature of the software is pretty good but upon exporting the footage to any format I'm finding the picture quality is very poor. Blacks seem to pixilate and the whole picture seems 'soft' even though I shot it on DVCAM.

Have I done something wrong in the capturing stage or export stage that I could rectify this with?