shaky display

When importing DV tape media from a camcorder the main display of iMovie shows a very shaky image which is very disturbing. The display on the camcorder is stable, and the imported media appears fine. I am using a SONY DV tape camcorder. Also there are times when I get a stable or reasonably stable image. Any ideas about what is happening? Using iMovie 10.0.5 and iOS 7.1