DSLRs aren’t designed to record high-quality audio; they lack professional inputs for microphones and have an auto-gain (AGC) circuit th...
DSLRs aren’t designed to record high-quality audio; they lack professional inputs for
microphones and have an auto-gain (AGC) circuit that ruins any chance of manually setting
your levels. This has changed with the recent introduction of Canon’s firmware upgrade for
the 5d, which enables manual audio recording, so it’s not to say you can’t record theatricalquality
audio on your DSLR production; you just need the right equipment. Essentially, you
have two options for audio recording: on-camera, or separate-system. On-camera is what
any video camera user will be familiar with; you plug in your microphone(s), and the audio
is recorded together with your video. Separate-system is what filmmakers accustomed to
shooting celluloid will be familiar with; you record visuals to one medium and sounds to a
separate recorder, and then have to sync the two
up during editing (thus the need for a clapper on
shoots). Both approaches have their pros and cons
(briefly: separate system affords you higher quality
audio recording at the expense of convenience in the
editing room; on camera is the converse), and which
approach you go with will depend on your production
needs and whether you even have the option of oncamera
recording (your DSLR may not have a mic
input, or you may be unable to disable the auto gain).
For a series of very helpful DSLR audio recording tests
watch Jon Fairhurst’s roundup of audio recorders (he also makes uncompressed audio
samples available):
1. Boom Mic
2. Camera Mounted Mic
3. Wireless Lavalier
4. Foley
5. Noise
6. Conclusions
To record pro-level audio in-camera, you will need a device to connect your microphones
(usually a XLR connector) to your camera (in the case of DSLRs, the audio input is a
consumer-grade 1/8″ stereo jack). The consensus on “best pre-amp/XLR adapter” is
the Juicedlink CX231 ($300). It offers pristine mic
pre-amps, good construction quality, very low noise,
and phantom power for your mics (if you don’t need
phantom power, the CX211 is cheaper). To use it, you
screw the Juicedlink onto the bottom of your DSLR (or
attach it elsewhere on your rig), plug in your balanced
XLR audio cables into the Juicedlink, and run the
included 1/8″ stereo cable to your DSLR’s mic input.
There are still a few issues — namely, headphone
monitoring is in mono and the levels are quite low. To address these problems, Jon
Fairhurst recommends a Boostaroo headphone adapter to achieve a usable monitoring
volume (I’ve found the Boostaroo makes the audio approximately twice as loud, which is
adequate for most situations).
If your DSLR doesn’t offer manual audio settings, the JuicedLink DN101 offers a solution
to defeat DSLR auto-gain. But whereas the 5D’s new manual settings allow you to retain
both channels of audio, the DN101’s hardware solution gives you one channel instead of
two (it defeats the AGC by blasting the unused channel with noise). This is fine if you’re
recording one microphone, but if you want two discreet channels of independentlyadjustable
audio and your camera doesn’t offer manual audio input levels, you’ll have to
go separate-system. It’s worth noting that Beachtek also offers a DSLR solution, but its
tone-based method of defeating AGC is, in my opinion and a lot of others’, unusable for
pro audio (this newer version I linked to is reportedly improved, however). Additionally,
JuicedLink is now offering the DT454, which builds in the AGC defeating tone as well as
level meters and a headphone monitor.
As with any XLR adapter of similar size, a Juicedlink or Beachtek can also double as a
riser plate on your support system. Furthermore, the Juicedlink website offers a catalog
of very helpful audio recording tutorials — indispensable if you find yourself trying to
turn a friend into an audio crewmember.
If on-camera audio recording isn’t an option for
your DSLR — or if you have a need to untether
your audio from your camera — there are a
number of quality flash memory recorders
available at very inexpensive price points.
One of the most widely-used is the Zoom
H4n (review, review), which records at (up to)
24-bit/96kHz on SD or SDHC cards. It offers 2
XLR inputs, a built-in stereo mic, and offers 4
tracks of simultaneous recording, which enables
the ability to simultaneously record its own
stereo pickup in addition to audio from the 2
XLR inputs; for filmmaking where foley won’t be possible, this can offer a nice mixing
alternative, in that you can adjust separately-recorded ambient levels independently
from your boom and lav levels. Having such a scratch track, assuming the H4n is
protected by a windscreen and is well-positioned, can be a boon for post-production
turnaround time on low-budget shows that have web, mobile, or low-end TV releases in
mind. At $350, the H4n is a great deal. One alternative: The Tascam DR100, which others
review well, but I witnessed the silver jog dial fall off repeatedly on a shoot (YMMV).
In addition to these two methods of recording,
there’s a third approach: purchase a CX231 to enable
on-camera audio when you want it, and add a flash
memory recorder for separate-system sound when
the production calls for higher quality audio or needs
the recordist to roam. A top choice for this purpose
is the Sony PCM-D50, which is similar to the H4n in
size and functionality, but it only accepts a 1/8″ stereo
input. However, when connected to a CX231, the
combination offers a great combination of mic preamps
and recording medium — you could use this
recording setup for a feature film, the self-noise is so
low. Videographer/reporter Dan Chung has reported
good results, and my own tests to date have confirmed
this (however, your audio will travel over an unbalanced 1/8″ cable for a short length, so
you’ll have to be vigilant for interference). An important feature of the PCM-D50 (review,
review) is its built-in limiter, which records each input at two levels simultaneously
and automatically switches to the lower level if clipping results at the higher setting.
For DSLR-based crews where the audio guy might not be a union man with decades of
experience, this extra fault tolerance is crucial. Other advantages include 4GB of builtin
flash memory (good for 6 hours of 48kHz audio), a 5-second pre-buffer (you can
automatically start the recording 5 seconds before you pressed the button in case you
weren’t rolling for something), and a real, rideable input level knob (instead of the H4n’s
pushbuttons). Disadvantages to the PCM-D50 include its higher price, its 1/8″ input, and
its reliance on proprietary Memory Stick cards (honestly, Sony, still?).
SPONSORED BY NOFILMSCHOOL
www.nofilmschool.com
No comments