What I've learned after producing almost one thousand interviews is to anticipate, to illuminate, and to compose within and then outside compositional rules.
Anticipate
While this is not a photographic technique, this concepts drives what I do photographically while filming an interview and it is relatively simple: listen to what is being said and anticipate non-verbal expressions and reactions during the interview.
If the person being interviewed is telling a story, I will always start by framing them up in a standard medium shot with enough room in the frame to allow their gestures to be seen. Typically this is framed from lower torso to the top of the head with enough headroom to balance the composition.
When the person being interviewed becomes more involved or emotional within the interview I'll slowly push into the person or if the the producer is asking a question off-camera, I'll quickly bump in close and pick up my filming with the subject framed closer, typically just below the collar bone to just below the top of the head, looking something like this:
While shooting the interview I do not lock down the head of the tripod. I maintain enough drag to keep movements from being too sudden, but loose enough to pick up any action of the subject. If my subjects looks down, for example, I'll float the frame down with them, using the focus of their eyes as a vector for the direction of my film plane movement. Should their eyes go their hands, I'll let the frame drift down to them, linger there for a moment and then crawl the frame back up to their face.
Since much of what we say is non-verbal, and much of our non-verbal expression is outside the scope of the face, I find it better story telling to pick up on these cues, anticipating where the subject's emotion or tension might be focused. Often, the hands are a great place to look.
Composing Inside and Outside the Rules
I'm hoping you have noticed that this image of Brock breaks some rules of composition, how he is composed and lead in the frame. The term lead means the direction the subject is facing and the space they are facing into is called lead-room or nose-room. Were this composition framed according to these guidelines, Brock would be positioned more camera-left since his body and face is turned camera-right. For the purposes of this interview, a graphic element would come in over the white negative space on the left side of the frame, and the talent had an edge to him, an attitude that played better having him composed in this way.
