update the drivers, are you using other software to render the video? I don't use a Mac but if you have access to a PC try the cam out on there to see if you can replicate the problem. If yes then it's the camera...if not there might be some settings that need to get tweaked. I have not had that issue on my Windows 7 machines (I have 2). Also, check the Logitech forums to see if others are having this issue as well as the mac forums.
I hope you work it out!!
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