The sound on most DSLR’s for the most part doesn’t measure up especially if you only use the built in microphone. What we use is two fold approach. First, we use an external Rode Video mic on each camera to record ambientbackground sound and as a backup. Second we use a Zoom H4N with two mic’s plugged in (with the built in mic’s and the two external mic pickups you have 4 inputs). We use the two external mic’s (usually on a boom pole) to record the actual conversations of the scene. On occasion (interviews or where a scene allows it without detection) we use wireless lavalier mic’s connected to the H4N to capture the converstations . To achieve a synch point we use a clapboard to begin each take. In post it is easy to synch the clapboard spike across all the sound tracks.
This method has proven to work very well for us in just about every situation we have come up against.
