Audio For Film 101: How To Get The Best Audio From Your DSLR
DSLR cameras are the go-to filmmaking tool for a huge portion of filmmakers. Smartphones, compact recorders, and pro video cameras each have their virtues and uses, but for most, DSLRs are more than capable of handling whatever you throw at them. They are versatile, produce great quality video and are relatively affordable. There’s one problem though: DSLRs do not record good audio.
If you’re a DLSR filmmaker, it’s probably one of the first things you noticed when you started shooting on one. For most purposes, the internal mics in DSLRs are practically useless. And so you’ve likely faced the question: how do I get better sound from my DSLR? There are a couple of things you need to consider. Let’s take a look!
Get a Good Mic
The first step is to get yourself a quality mic. For this article, we’re going to be looking at using an on-camera mic like one from our VideoMic range. These are great for lots of reasons. Firstly, they’ll infinitely improve the quality of your audio but won’t break the bank. Armed with a DLSR and VideoMic (plus some videomaking skills of your own) you can create pro-quality video to rival rigs worth thousands of dollars. Secondly, they are compact and unobtrusive, and they are quick and easy to set up and operate, giving you complete freedom when shooting.
Lastly, they are very versatile – VideoMics can be used for a huge range of audio capture needs for filmmaking, from recording dialogue to tracking Foley to capturing on-set ambiance. Our VideoMics (with the exception of the Stereo VideoMics) are designed to pick up sound sources directly in front of them and reject sound from the rear and sides; this means they will focus on what’s in front of the camera, allowing you to focus on what you’re shooting and not where your mic is facing. If you do have someone dedicated to recording audio on set, our VideoMics can also be great boom mics. Or if you’re recording Foley, simply stick your VideoMic onto a Joby mount and get nice and close to your subject. Take a look at our VideoMic range here and check out our article on some different uses for your VideoMic.
Turn Off Automatic Gain Control
Most DSLR cameras have a feature called Automatic Gain Control (ACG). Make sure this is turned off! This is very important. ACG automatically adjusts the recording levels on your camera on the fly according to the volume of the sound it is picking up. It sounds like a handy feature – kind of like a compressor/limiter. The problem is that is doesn’t work very well. In fact, if you have a video mic plugged in, it will almost definitely ruin your audio – your levels will be all over the place, background noise will be amplified, and when you start talking it will quickly turn it down, making the first few words you speak uncomfortably loud – and even distorted – compared to the rest of your sentence. Scroll through your camera’s menu, find the auto-gain setting, turn it off and leave it off. Period.
Bypass Your Camera’s Audio Settings
While you’re in your camera’s audio setting, take a look at what else you have control of and what you can turn off. As a rule of thumb, the only thing you should be worried about is your gain settings (we’ll get to that in a moment); everything else can be bypassed, unless you know exactly how it works and that it will definitely improve your audio.
Most DLSRs will have a limiter, wind noise reduction, and ACG (yours may have other EQ or gain controls) – switch these off. They are designed for when you are using the internal mic, and you will achieve far better results with a VideoMic and by editing your audio in post-production. You shouldn’t need a limiter if your gain is set correctly, it will only serve to make your audio sound over-compressed and uneven. And there are lots of other ways to reduce wind noise that are more effective and will ensure your audio is clean and clear.
Watch Your Audio Levels
Your DLSR’s audio levels are the only thing you need to worry about when recording – and they are very important. Different cameras have different preamps – some better than others – and they will all handle incoming audio differently. Yours may be particularly ‘hot’, meaning it will be easier to overload your preamp, causing distortion. Or you may find you need to boost your audio levels to get a nice, strong signal. The latter is less common for DSLRs, most have quite hot preamps.
Audio levels are measured in decibels (dB), usually on a numbered minus scale, with zero being maximum volume. On your camera, your audio levels will be represented on a vertical or horizontal meter on your screen. The golden rule of setting audio levels is to make sure your meter never hits 0db – this may cause your signal to clip, which will result in distortion. We all know how unpleasant this is to listen to, and there’s very little you can do about it in post.
To be safe, your audio levels should always sit well into the minus dB range – the ‘green zone’. The ‘yellow zone’ is your safety net – an indicator that your level is creeping towards 0db. The ‘red zone’ is where distortion will happen. Stay in the green zone, giving yourself plenty of ‘headroom’ before your levels start peaking in case your sound source suddenly gets louder. You also don’t want your audio levels to be too low as they may lack punch and clarity when you boost them in the editing stage. Around -12db is a good area to aim for.
If you are recording a dynamic and unpredictable sound source (say, a football game or a particularly spirited talker), watch and listen for the loudest moment and adjust your audio levels so this sits just under the yellow zone at this peak. This will ensure that your signal never clips. If you’re worried about the quietest parts being too quiet, always remember this can be boosted in post-production using compression.
If your VideoMic also has a gain control – the VideoMic Pro, for example, which has a three-position gain control (-10db, 0, or +20db) – remember to balance this with your camera’s audio levels. You should always try to not strain your camera's preamp. Since they are usually low quality, making them work hard to boost a low signal will introduce more noise to your audio. Using a VideoMic with the +20dB gain boost can really lighten the load for the preamp and give you a much cleaner signal.
Monitor Your Levels With Headphones
Many modern DLSRs have headphone outputs for monitoring your audio, and these are super handy for making sure your levels aren’t clipping, there isn’t any extraneous noise, or anything else that might ruin your audio. Always make sure you have a pair of headphones handy (chuck an extra pair of earbuds in your kit bag just to be safe!) and use them whenever you’re recording. If your camera doesn’t have a headphone output, you may want to look into getting an external preamp.
Use an External Preamp
The preamps in DSLRs aren’t great. If you’ve got yourself a good microphone, you may want to go a step further and buy an external preamp too. While this isn’t a must, it will definitely go a long way to improving your DSLR’s audio. There are two ways to go for preamps: on-camera and an entirely separate recording setup. For most DSLRs, external on-camera preamps are more than enough. These slot directly onto your camera’s cold shoe mount (and will have a cold shoe or two of their own for mounting your mic) and they plug directly into your camera’s input, meaning you won’t have to worry about syncing the audio in post as you would with a separate recording set up.
One thing to remember is that these will not completely bypass your camera’s preamp, so you will have two gain stages to set (three if your mic has a gain control). So that you don’t have to worry about adjusting your in-camera audio levels to compensate for the external preamp, just set them quite low – well away from the yellow zone – and leave them be. Your external preamp should give you all the control you need.
There are many other factors that will impact your sound – how you position your mics, where you are recording, how you edit your audio in post and so on – but if you follow these steps, the audio from your DLSR should be clean and clear. Find out more about the RØDE VideoMic range here.