Today I ran some simple audio tests with a Canon 5D Mark II. My plan was to record audio with the onboard microphone and with an external microphone. Recording audio with the onboard microphone is simple. One just points the camera at a subject and presses the ‘Set’ button to initiate video recording. The 5D Mark II doesn’t provide much in the way of manual audio controls. For example, there is no way to turn off the automatic gain control (AGC) which can lead to sound booming in the recording. Also there are no balanced inputs, so an XLR adapter is required to connect professional microphones.

Canon 5D Mark II with juicedLink XLR Adapter

In general it’s better to use external microphones to capture high fidelity recordings. In the case of video cameras, the mechanical action of the camera is often picked up by the internal microphone. However the Canon 5D Mark II is very quiet since it has no moving parts during recording. Another reason to use an external microphone is to position the microphone closer to the sound subject. This helps cut down on reverberation noise and yields a better signal to noise ratio. Also a much higher quality microphone may be utilized which out performs the camera’s internal mic.

External Mic Running on Phantom Power

After reviewing Jon Fairhurst’s thorough review of the audio recording options for the 5D Mark II, I chose to use a juicedLink XLR adapter. Specifically I’m using the two port model CX231. I seriously considered using an external recording device such as the Zoom H4N. Using the Zoom product would mean I’d have to sync the sound to the video in post, although having the ability to record 24 bit audio at 96 kHz does have its advantages. However for now I decided to stick with a synced-sound solution. For an external microphone, I’m using a Sennheiser ME 66 with phantom power coming from the CX231 XLR adapter.

XLR Adapter Designed for a Camcorder

The juicedLink CX231 was designed for a video camera, so the Canon 5D Mark II looks a tad out of place when secured to this XLR adapter. However this does not impede its use in anyway and, unlike the BeachTek DXA-5D, the CX231 does not block the battery compartment.  I didn’t think this was a big deal on first look, but having easy access to the battery proved vital as later described in this article.

By utilizing the XLR adapter of your choice, one may then feed external audio to the Canon 5D Mark II during recording.  This works fairly well except, as mentioned before, there is no way to disable the AGC.  Since the AGC attempts to keep the ambient audio levels at a constant, a dynamic acoustic environment causes recorded audio levels to be all over the place.  Therefore it’s usually recommended to disable AGC.

There is a work around to the audio AGC issue, but it involves tapping a non-standard solution. The Magic Lantern Firmware addresses this and other short comings in the Canon firmware. This software is an open platform for developing enhancements to the Canon 5D Mark II. It runs along with the Canon firmware, as opposed to replacing it, and addresses a number of the video limitations. Along with having an option to disable the AGC, it also provides on-screen audio meters, zebra stripes, custom crop marks, and control of focus and bracketing. Although the Magic Lantern firmware runs in RAM and does not overwrite Canon’s ROM-based firmware, I have to admit that I was apprehensive to run this software on my camera. Although the firmware has been tested by many people, the thought of having rogue instructions transforming my new 5D Mark II into a brick is quite unsettling.

Magic Lantern Firmware Loaded

In the end, though, I read enough positive reviews of Magic Lantern to give it a try. Without a way to disable AGC, I would be better off capturing audio with an external recorder. Since I decided I wanted a sound synced solution, I moved forward with the Magic Lantern firmware.

Fortunately the install instructions on the Magic Lantern site are straight forward. Basically you copy three files to the root folder of the CompactFlash (CF) card, and update the camera firmware from the menuing system. There might be a way to copy these files with the EOS utility, but I ended up buying a CF card reader for $30. Once the firmware is updated with the Magic Lantern software, new onscreen icons and guides will be visible in the live display. Also the left and right audio meters will be visible at the top of the LCD.  When you power down the camera, the Magic Lantern firmware is removed from RAM and has to be reloaded again upon camera power up.  I think I read something about a configuration file on the Magic Lantern site, but I don’t mind reloading the firmware since it’s a fast operation.

I would like to say that all went well and I didn’t encounter any issues with the Magic Lantern firmware.  However I did notice that, sometimes, if I powered off the camera with the live display on, the camera would not turn on again.  After toggling the on/off switch a few times with no results, I tried removing the battery. This halted any instructions that were running on the camera processor and allowed the camera to turn on once the battery was put back.

This isn’t a huge issue, and one that I’m willing to live with to get synced audio. However if I had gone with the Beachtek DXA-5D, I’d have to remove the XLR adapter every time the camera hung to pop out the battery. With the juicedLink CX231 I have clear access to the battery, and don’t have to disturb the camera setup to reset a hung camera.

Here is a short video showing recordings with the onboard microphone and an external microphone.

Canon 5D Mark II Audio Comparison from Fourth Order Light on Vimeo.