Sound For Video DSLR Shooters - A Small Step Up
Sound is a huge part of what makes any video good or bad. The new Canon Rebel T2i (also called the Canon 550D in Europe) is the first Video DSLR I am aware of that has given the issue of sound at least some preliminary thought. It's still not a "professional solution" but compared to other cameras in its class - it is a step up.
Basically all the other cameras have just awful built in microphones for capturing sound! For instance, if you look at the front of the Canon 7D you will see about 3 tiny holes in the upper lefthand area - believe it or not that's the microphone. The Canon T2i allows you to connect an external stereo microphone to the camera but I still wouldn't probably use it as my final sound source.
In the first draft of this posting I wrote that the tiny built-in microphone is "good for nothing" but in truth it does serve one important purpose which I talk about below.
To save costs, camera manufacturers like Canon have gone a step further to make their built-in microphones on Video DSLRs even more useless by incorporating "automatic gain control" (AGC) software.
What AGC does it try to keep sound levels consistent by raising the volume on the sound it captures whenever it thinks the levels are too low.
Here's the issue: "Silence" can be good - if you raise the levels on the quieter parts of your audio willy nilly you will also be introducing a lot of noise - so if you are recording an interview and there is a pause, the camera may decide to suddenly increase the volume meaning you will now be hearing a bunch of amplified background noise and then when the interviewee speaks again, she may be way too loud until the AGC has a chance to bring the volume back down again to the earlier level.
Okay, so what are you to do to fix this problem? Two suggestions I have for you are:
1) Don't just record your sound using the camera's built in microphone, capture the sound on two devices at the same time. What I mean is that you should also be capturing sound separately on a high quality digital recording device like the Zoom H4n from Samson.
Hollywood movies have been recording audio this way for at least 50 years - yes, the film they shoot is basically silent. They record the sound separately and then combine the film and audio together later. That's what that guy holding the boom pole is doing!
Getting back to the Zoom, it has both built in stereo mics that are really good quality AND you can also connect up two other external microphones - meaning you can record up to 4 tracks simultaneously. The Zoom H4n costs $300 and is worth every penny.
2) If you edit in Final Cut Pro, check out an application called "PluralEyes" - it's about $150 and will save you hours of frustration.
You are probably wondering how you would get your sound to sync up to your video if you were to go the route I am suggesting. Granted, you could use something like a clapper board but they can be a bit a bit of a pain. What PluralEyes does is allow you to use the terrible audio captured by the camera as what you might call a "sync" track.
You import the good audio into Final Cut and place it wherever you want in the timeline. Then the PluralEyes software matches the waveforms from the two audio sources and moves the good audio into its correct position - so that now your high quality audio is in perfect sync with the bad audio captured by the camera. It's not foolproof but it has so many advantages it would be foolish to try to do it yourself.
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Reader Comments (3)
UPDATE: The Owner's manual for the Canon T2i has just been released and it appears from reading it that the sound capabilities are the exact same as on the Canon 7D. Both cameras allow you to use external microphones with STEREO mini plug (3.5mm diameter) connections.
Well, even though I probably will connect something like a Rhode VideoMic to the camera to provide an improvement over the built-in microphone I will still be relying on externally recorded sound for my high quality sound source.
Both the Canon T2i and the 7D employ the Automatic Gain Control circuitry I was talking about which would be in effect even with an external mic plugged in.
This is really useful information Steve. My friend told me about this blog and the above points summed up nicely what I had discovered over months of research. I looked at the Panasonic GH1 as it had the external stereo sound options but autogain as you point out will be an issue even there and you'd need a mixer I think. Nice auto focus in video mode though.
We made a trailer using a Canon 5D Mark II and synced the separate sound files with the clapperboard using the camera audio simply as a reference. Having a decent soundtrack makes all the difference to the final product so I think it's worth the time and investment if you have great looking footage.
The sound man I used hired a 744T to match the recording rate to the 30fps. That unit costs thousands to buy so I've been looking at the Zoom H4N.
I'm not too familar with the frame rate to sound rate matching but in tests with the Tascam DR-100 (similar to H4N) my 30fps footage taken on a Canon 500D looked okay.
If anyone is interested in how the 5D MKII film project worked for us feel free to check out the trailer for Six Magic Numbers and see what you think.
Sorry if this has turned into a long comment :-)
Very cool video Martyn, probably the most extensive video effort I've seen for a book promotion even from the major publishers, great job!
Another new piece of kit is the Beachtek DXA-SLR adapter which allows you to defeat the automatic gain control and to attach two professional mics with XLR connectors to your 7D, 5D Mark II or T2i/550D. It also includes the ability to monitor live sound. It's a solution I'm very interested in.
For more information on video DSLRs make sure to read Philip Blooms blog - right now he's the foremost expert I know on the topic. Best of luck with the book!