When filming outdoors, your choice of mic and how you deploy it, will be down a combination of to several factors, including how noisy the shooting environment is, how mobile you need to be during the shoot, how busy the area is, and how many subjects you’re actually interviewing. Adverse weather conditions may also impact on the speed at which you need to deploy your gear.
In a particularly noisy environment, a lav mic would probably be the obvious choice and depending upon how much time you have with your talent for rigging the mic. If you were conducting a single interview that was to last for several minutes in one location, you might be happy to use cables to connect to your camera. If the area was particularly busy however, this might present complications like potential snagging and tripping hazards for an unwary member of the public. At a busy festival, for example, wireless would most definitely be a better choice.
If you don’t have a wireless lav, or if you’re interviewing multiple talents, and would, therefore, need to rig and retrieving a wireless lav system repeatedly, you may prefer to using a camera mounted shotgun mic. If this is the case, it’s important that you get in as close to your talent as possible and shoot with your lens at a wider angle to frame your subject and their surroundings appropriately. If you find yourself stepping back and zooming in to achieve suitable framing, which in other circumstances may well be the way to go, you will be increasing the distance between your mic and talent and effectively reducing the ratio between your target sound and the background noise.
An alternative solution, for faster moving outdoor shoots, is to use a handheld shotgun mic with an XLR transmitter, like the Sennheiser SKP 500, Rode TX-XLR or Saramonic TX-XLR9. This is often the preferred choice for newsgathering teams, who want the benefits of good mic proximity, but who don’t necessarily want to rig a wireless lav system, as this takes time to do effectively. If you plan on using an XLR transmitter as part of your wireless system, it’s important to check that either your shotgun mic can be battery-powered, or that your choice of XLR transmitter delivers phantom power.
If you’re using a shotgun mic outdoors, either on camera, handheld, over cables, or wirelessly, it’s crucial to use a decent shock mount, because otherwise any handling noise from handling the camera or from handling the mic itself will be picked up. In addition, regardless of what kind of mic you’re using, when recording outdoors it’s always a good idea to use a wind screen or Deadcat, as even a slight breeze hitting your mic can sound like an express train running through your set.
Depending upon the type of camera that you used, there are three main methods for recording audio that you could use:
- Recording directly to your camera via by plugging a mic into your camera’s mic input.
- Using an external mic preamp or mini mixer to condition the microphone signal before going to the camera.
- Using an external field recorder to record your audio and then synchronising this to your video in post-production.
If you’re using a device that essentially originated as a still camera, and that has been adapted more recently for the world of video, e.g. a DSLR, mirrorless or compact camera, recording directly to the device isn’t recommended. This is primarily because, in the same way that their onboard mics leave much to be desired, in all but a few cases, these devices have a well-deserved reputation for low quality, noisy preamps. In addition, these devices tend to only record audio at 16 bits, which reduces the available dynamic range (the difference between the loudest and quietest signal that can be recorded) significantly. Another issue is that ‘still’ type cameras don’t support phantom power, so if you’re recording directly to this type of device, you will need a shotgun mic that has its own battery power supply, like the Rode Video Mic Pro+ or the Sennheiser MKE600. Lav mics invariably require ‘plugin’ power, which is provided by most ‘still’ type cameras and mobile devices, but you should check the specification of your equipment before making a purchase.
Using an external mic preamp increases the gain of an external mic signal, allowing you to reduce the gain on your camera’s audio input to a minimum. This effectively eliminates the problem of camera preamp noise and gives a much cleaner audio signal going to the camera. In addition, camera mounted mic preamps, like the Saramonic SR-PAX2, often provide additional features, such as supplying phantom power to external shotgun mics that don’t provide their own battery power, and the ability to mix signals from two or more mics. What this method doesn’t do, however, is overcome the dynamic range restrictions of 16-bit recording.
Alternatively, you can use an external field recorder, such as the Tascam DR60, to record your audio, taking advantage of both better mic preamps and 24-bit recording. This does mean that your audio track will require synchronising to your video in post-production, but many shooters think this is a small price to pay for higher quality audio. Field recorders tend to offer an array of options for conditioning audio signals, mixing two or more mic inputs, and discretely preserving the input from each separate mic, in order that mixing can be done, at your leisure, in post-production. Field recorders also supply phantom power to microphones that need it.
If you use an external recorder, you also need to simultaneously record the audio into your camera. This gives you a reference audio track, which is embedded in your video files, that can be used to sync your high quality externally recording to in post-production. It is possible to sync to video footage alone, but this is much more challenging and time-consuming to do. You can do this either by connecting the two devices with a mini-jack cable or by recording with your camera’s built-in mics. A single loud handclap at the start of every take will make syncing audio fairly easy, because all you now have to do is align the audio spike from your external recorder’s audio track, with that from your camera’s onboard mic.
Professional grade camcorders and cinema cameras tend to have good quality mic preamps and are more likely to record at 24bits, and also supply phantom power, largely negating the need to use either an external preamp or external recorder.