In this new era of capturing movies with DSLRs, the Achilles’ heel is definitely sound, with the current crop of video DSLRs all lacking professional sound-recording features. The cameras don’t allow you to manually control sound, nor do they contain XLR inputs for professional microphones. To obtain good sound, many video-DSLR users are taking it “old school” by recording dual-system sound in which a separate sound recorder is capturing sound independently and untethered to the camera—similar to a film production.
Although you’ll definitely have superior sound to your video DSLR, it does add extra time-consuming steps to the production process. First off, you’ll probably want an experienced sound person who can properly mix levels and write detailed sound reports since you end up with an extra media card with sound files that are independent to your video. During production, you’ll also need to use a slate or perform a handclap in order for your editor to sync up the sound and video clips in post. (Postproduction sync can be a very time-consuming process, especially without detailed sound reports.)
|Input: 2 XLR balanced inputs
Output: 3.5mm stereo jack
Phantom Power: 48V min; 12V min power-savings mode extends battery life
Frequency Response: ±1 dB typ, 20 Hz to 20 kHz
For those of you who aren’t inclined to go through these extra steps, a good solution is an XLR adapter/preamp, which attaches to your video DSLR and lets you set your sound levels manually. The juicedLink CX231 is a great solution—an XLR audio adapter, mixer and preamp that enables connection of balanced audio signals to the 3.5mm stereo input jack on your video DSLR or camcorder. The unit is also capable of receiving input from wireless mic receivers as well as phantom power.
The frequency response is very impressive at ±1 dB typ, 20 Hz to 20 kHz, which is 13 dB better than their nearest competitor of audio-adapter devices. For power, a single 9V battery is utilized, which should power the CX231 for up to 16 hours. The unit is constructed of black anodized aluminum enclosure and mounts to the bottom of the camcorder or DSLR, which then can mount to the top of a tripod or camera head. For use with a video DSLR, one of the smart things about the design of the CX231 is that you still have access to your camera’s battery port without having to remove the unit to change the camera’s battery. The juicedLink CX231 has a list price of $299.
But there’s still a catch to the process of single-system sound for video DSLRs. The cameras don’t provide some valuable features for achieving great audio. One important feature is manual override of the AGC (automatic gain control) circuitry. However, if you’re a Canon EOS 5D Mark II owner—the most popular video DSLR because of its full-frame sensor—there’s free software that unlocks these features for you. Magic Lantern is a third-party firmware upgrade that enables a user to turn off the camera’s AGC and manually control the gain. In combination with the CX231, you can achieve signal-to-noise performance rivaling standalone audio recorders. Additionally, the firmware upgrade displays on-screen audiometers, plus capability for monitoring out the 5D AV-out jack.
Along with sound capabilities, Magic Lantern provides rudimentary zebra stripes, custom crop marks for various aspect ratios and other features. But the AGC kill is the most essential feature for the download. Be forewarned: The free firmware upgrade is distributed with no warranty, and no guarantees are provided. Use at your own risk.