Recording Broadcast-Quality Audio on the Canon 5D Mark II DSLR Camera
Despite its limitations as a video camera, the Canon 5D Mark II DSLR remains a popular choice for filmmaking and video production because of its superb image quality, small size and great selection of lenses. Many accessories have been manufactured to address limitations such as focus and bracing. In my opinion, however, the camera’s biggest issue is its near inability to directly record broadcast-quality audio. After many trials and field tests, I have created an solution that enables the camera to directly record superb audio.
Here’s the set-up
At the heart of my set-up is the Sound Devices 302 3-channel audio mixer, at right, which has some of the best pre-amplifiers on the market. The mixer provides three XLR audio inputs and a standard left and right XLR output. From the mixer’s XLR outputs, I use a custom-made XLR to mini-1/8″ cable that plugs directly into the camera’s MIC input jack.
Custom made cable that connects the mixer’s XLR left/right output to the camera’s 1/8-inch mini stereo input.
To bypass the 5D’s pre-amps, I manually set the audio level in the camera menu to one step (or one “click”) above zero. See the image below.
Although the mixer’s outputs are considered line-level, I reduced it by -12db, which is done through the 302′s custom set-up menu. By reducing the output from the mixer and keeping the camera’s audio level set one click above off, I’m able to feed a clean signal into the camera and bypassing the noisy pre-amps. The result is a very clean audio track that’s locked to the video.
Even with the adjustments, the audio coming into the camera from the mixer is still a bit too high. To compensate, make sure to keep my audio level averages down around -18db to allow for extra headroom, which is the difference between the highest signal level present and the highest point on the device before distortion occurs.
Because the audio being recorded directly into the camera cannot be monitored (there is no headphone jack on the camera), a back-up system is important. The 302 mixer has a mini-XLR, stereo “tape” output that is the same as the regular XLR outputs. This is perfect for the connecting a digital audio recorder. I connect a Zoom H4n recorder using a 1/8″ mini stereo to mini XLR cable.
This set-up has worked for more than 300 hours of footage over three documentary projects. But despite the success, it’s not perfect. The 1/8″ mini connector can come loose from the camera. Since there’s no way to monitor the actual camera audio, there’s no way to tell what’s being recorded so you won’t know there’s a problem until you can check the video files later.
Where’s the problem?
The problem lies in the camera’s audio pre-amplifiers. Pre-amps amplify the incoming microphone-level audio signal to a line-level signal, which is much less noisy. Professional quality pre-amps eliminate the signal noise. Canon used lower-quality pre-amps in the 5D II so when a microphone is plugged directly into the camera’s “mic in” jack and the audio level (gain) is turned up, a distinct hiss is present. For filmmaking and broadcast applications, this is unacceptable.
Many articles have been written about how to circumvent the camera’s noisy audio pre-amps by recording audio separately with a digital recorder and later syncing it with the video in an application such as PluralEyes. I’ve used this method in the past and it works pretty well but now it’s an unnecessary step.
The key is to use a hardware solution to bypass the camera’s pre-amps. I arrived at this setup after extensive testing with off-the-shelf audio solutions for the 5D. While testing third-party devices from BeachTek and juicedLink, which boost the incoming audio signal, I realized that a standard audio mixer would do the same thing. None of the devices on the market provided the noise-free audio at the quality I required for documentary film production.
Most of my field work is either alone or with one other person. To provide maximum flexibility, all the audio gear fits in my waist bag. This way, I can work alone or in conjunction with a sound person. (There’s a diagram below that illustrates how I wirelessly connect to a professional sound person.)
In addition to the audio gear I’ve described above, I use a Sennheiser ME-64 microphone on top of the camera. A Rycote “Softie” is mounted on the ME-64 to cut wind noise. A coiled XLR to XLR mic cable runs from the camera-mounted microphone and into the channel one input on the mixer. The two other mixer inputs are used for wireless microphones. Sony MDR – 7506 are my preferred headphones because they sound good in various sound environments and are virtually indestructible.
Initially, being tethered to my waist bag concerned me but now I’m completely comfortable having everything together in one place. The ThinkTank bag is constructed with small openings to weave cables easily through the interior compartments so everything stays organized.
As you can see in the above photograph, I tend to use my waist bag for multiple purposes, such as a tripod platform to steady my handheld shots.
Working with a sound person
The diagram below shows the technical set-up when working with a sound person.
Click here to view PDF version of this diagram. ©2010 by Brenda Chen – published with permission.
For an extended period in 2010, I had the pleasure of using this set-up while working with filmmaker/journalist Bob Sacha on a three-film project for the Open Society Foundations campaign to Stop Torture in Health Care. All three films for the project were shot on the 5D using this set-up. Because Bob and I had duplicate, identical gear, we were able to seamlessly alternate between shooting and collecting audio on a daily basis.
My set-up is a result of field-testing by a number of people including; Travis Fox, Bob Sacha and Roger Phenix. This set-up would not be in existence without the generous loaning of brand new equipment by Rich Topham, Eric Perez and staff at Pro-Sound Services in New York.