Positioning microphones so that they aren’t in your shots while making sure they can capture quality audio can become highly frustrating. And it’s even more frustrating when you don't notice that a microphone got into a shot until post-production. At this point, you must be thinking that the footage is ruined, but Griffin Hammond has a trick that he uses to hide microphones in shots without having to reshoot anything.
https://www.youtube.com/watch?v=1Jv4wuZumbw
Whenever Hammond is conducting an interview and he accidently moves the microphone into the shot, he uses a mask in Final Cut Pro X to cover up the microphone, completely removing it from the shot.
“Most of the time, I shoot interviews pretty close, and it’s easy to keep the mic just below the frame. But … in a wider shot, sometimes I mess it up,” says Hammond. “Luckily, most of my interviews are on tripod, and all I have to do is find one clean part of the shot, mask that on top, and no one knows how often I make mistakes.”
In Final Cut Pro X, Hammond creates a duplicate of his video on timeline and uses the Trim tool to find a part that doesn’t have the microphone in it. He then drags Draw Mask onto the clip and is able to draw an area around the microphone after disabling the duplicate clip. The microphone then becomes hidden when Hammond re-enables the duplicate clip with its mask. Hammond also says that you can add some feathering to the mask, to ensure that no one will ever be able to see it.
This trick will not work, however, if the subject moves into the area of the mask, or if the camera isn’t mounted and moves or shakes.
Hammond uses this technique often. In the video, he says that he even positions the microphone in the shot purposely so he can capture the best audio possible, knowing that he can edit it out later in editing.
Hammond clarified in the comment section of the video that you don’t have to use Final Cut Pro X to be able to use this trick and says that you should be able to do this trick in Premiere as well. Any editor that support masking out portions of a shot should be able to accomplish the task.