I got here from FreshDV.
Looks like the C300 has some colour fringing issues when dealing with the edges of highlights. Hmmmm. Paul Antico has a detailed look at the scenarios that may lead to it showing up. He has been in contact with Canon, and they have told their engineers about it. It doesn’t ruin the camera, but it can affect some shots. It’s important if you’re going to be using the C300, to know what to look for and scenarios to avoid.