A small investment in an external microphone can make an enormous difference in the overall quality of your DSLR video without breaking the bank. So whether you're considering an on-camera model, handheld mic or lavalier, take some time and explore the possibilities. You'll be amazed by how much good audio actually improves the look of your video.
|Mics with 1/8-inch connections are convenient, but are less rugged than their pro cousins and are limited to cable length. Pro mics' signals can easily run 100 feet or more without problems. The key feature on pro mics are the three-pin XLR connectors—sometimes referred to as Cannon plugs—and adding the ability to use pro mics with your DSLR adds a huge level of versatility to your rig.
But why would a single-channel, professional microphone need three conductors? The magic comes from balanced-line technology. Using this approach, the mic's signal goes to pin #2, pin #1 carries the ground (shielding), and pin #3 has an inverted copy of the mic signal. Once the signal reaches its destination—camera, mixer, recorder, etc.—the inverted copy of the signal is flipped and added to the original. Any noise like hum or buzzing that the cable may have picked up along the way from sources such as AC cables, lighting or generators is also inverted and is cancelled out at this stage, while the original signal is unaffected.
That's great, but how do I get this signal into my camera's 1/8-inch mic input? Two inexpensive XLR-to-miniplug adapters—the Hosa MIT-156 and the Pearstone LMT100, each about $20—offer easy interfacing of a pro condenser (with onboard battery powering) or dynamic mic to your system and will route this mono signal to both channels of your camera input. To use two such microphones, you could try a passive (nonpowered) XLR mic interface such as the BeachTek DXA-5Da, Sign Video XLR-PRO, Studio 1 Productions XLR2-DV or Whirlwind Audio LMC2.
To use condenser mics requiring pro 48-volt "phantom" powering with your DSLR, you'll need an outboard mixer/preamp, such as the BeachTek DXA-SLR, JuicedLink CX211 or the just announced Fostex DC-R302—all of which are designed to mount directly under your DSLR to create a compact production package.