Recording dual system audio outdoors or in noisy environments

Some time ago I found myself on a boat, capturing footage of whales off the beautiful coast of South Africa. In between shooting the whales (with the camera that is) I was trying to get some good shots of Jason, co-owner of Ivanhoe Sea Safaris, who was explaining all sorts of interesting facts about the whales.

I was using my trusty combo of Canon 5D mark II plus Zoom H4n to record some decent audio. I quickly found out, however, as soon as there was some wind - which is all the time if you’re out at sea - or the engine started roaring, the audio from the in-camera mic quickly became unintelligible, making it a challenge to sync the audio with PluralEyes, or even manually.

If the H4n were mounted on the camera I could have easily fed its signal into the 5D's external mic input, but  I find that setup ergonomically cumbersome, plus the noise from focusing or merely touching the camera will be audible. So in this case my wife/assistant Brit was operating the H4n separately. Running an audio cable between two continuously moving people on a wobbly boat with other passengers moving around at the same time would not have been very practical, so afterwards I came up with a different solution.

The basic solution: wirelessly transmit the audio to the camera

Using my Sennheiser wireless kit it’s possible to transmit the signal from the H4n to the 5D, giving you a nice clean in-camera audio signal for syncing in post. This setup works for any noisy or windy environment where the camera's built-in mic might not alway be able to capture enough of the dialog or interview audio.

But wait, now the audio can’t be monitored since the transmitter is plugged into the H4n’s output. We can fix this by introducing a splitter, like so:

Splitting the audio signal from the Zoom allows for monitoring

You could even take this a step further and feed audio from an external mic into the H4n, a shotgun mic or a lavelier mic for example, and transmit its audio to the camera.

Go nuts! You can plug additional mics into the Zoom
There are two additional advantages to this approach. While the 5D does a mediocre job of recording audio even if you provide it with a high quality input, with this method the in-camera audio would actually be good enough to use in an edit if you were really pressed for time. Secondly, if you’re recording in a very dynamic environment, where the subject, camera, and audio operator move around a lot, you’ll find that the external and in-camera audio will start drifting out of phase simply because of the changing distances the sound waves have to travel from the subject to the two mics. Usually it’s barely noticeable, but it can make syncing difficult in some cases. If however the external audio signal is recorded into the camera as in this example, all the audio tracks will line up perfectly.

Hope this was useful. I’d be curious to hear if you’ve ever run into this kind of situation, and if so, how you handled it.

UPDATE: just after finishing this post I headed over to Planet5d.com and saw this interesting solution for reducing wind noise on the built-in camera mic. I guess there's no such thing as coincidence...