Hallo Bob, thank you very much for your help. My Zoom was really set to 44.1kHz. Now I have set it up to 48kHz/24bit and it worked! Video and sound is now in synch. Without your help I wouldn't have made it. But there is one thing I have to mention! My EOS 550D supports 30p, 25p, 24p, 60p, 50p...