Capturing high-quality audio should be one of the primary considerations when embarking on any kind of film shoot. A number of factors can influence the microphone requirements, and several questions should be considered when deciding what might work best for any given shoot. Are you recording dialogue or ambience? How wide or close are the camera shots? What type of content are you shooting? In this article we consider the top 5 microphone types to have in your filming kit to cover you in a wide variety of situations.
Shotgun Mics
Shotgun microphones are among the most directional and have a ‘Lobar’ polar pattern. Interference tubes or specially shaped slots on either side of the microphone body in front of the diaphragm help to cancel sounds arriving from the sides of the microphone, thereby making it very effective in situations where rejection of off-axis sound is required. This makes it well suited to use in noisy environments or where it’s not possible or practical to place a microphone in very close proximity to the sound source. Due to the way interference tubes work shotgun mics work best in acoustically dry envionments.
A common use of shotgun mics is on a boom pole above actors for the pickup of dialog. There are many lengths of shotgun microphone available and the one you choose totally depends on the nature of the job you’re working on. It should be noted that the length of the shotgun mic is directly proportional to the lowest frequency to which it maintains it directionality. In other words, to reject off-axis lower frequencies, you’re going to need a longer shotgun mic.
For most dialogue work, short to medium shotguns work well because they can be mounted on a boom pole and controlled by a boom op. They have a slightly wider pickup pattern than their longer counterparts and so are a little more forgiving of placement, albeit still pretty directional. Longer shotgun microphones are more directional and more unwieldy to operate on a boom pole and so generally are less well suited for use on dialogue where actors are moving around. Long shotguns work nicely in situations where they need to be placed quite far away from a sound source but can be mounted in a fixed position. This type of shotgun mic can be used for major sporting events where extreme directivity across a broad frequency spectrum is required. The polar pattern of a shotgun mic tends towards becoming hyper cardioid at lower frequencies, so be sure to select one of the right length for your intended application.
Lavalier Microphone
Lavalier, or lapel microphones are used in situations where actors or presenters need to be individually miked. They are typically clipped to clothing and the cables can be hidden out of sight within a person’s top. For use by presenters or in studio situations, it’s usually acceptable for the microphone itself to be visible, but for use on drama, it will need to be hidden, either within a costume or sometimes in hair. Both wired and wireless versions of lavalier microphones are available, with the wireless (radio mic) type being the most common. The mic is attached to a belt pack transmitter which can be placed in a pocket. Small belt pack-sized receivers can be attached directly to cameras or placed in a sound bag, or they can take the form of a larger rack mounted unit.
This type of microphone is indispensable when close pickup of a person is required but it’s not possible, or is impractical to use a shotgun mic on a boom pole. One important factor to consider when using wireless lav mics is the radio frequency on which they operate. Be sure to obtain a license when using frequencies other than those which are ‘free to air’. This varies from country to country but in the UK, channel 70 (863 to 865 MHz) can be used freely. Other frequency bands require a PMSE (Programme-making and special events) licence.
Lav mics can vary in cost considerably, with the most expensive offering features such as digital transmission, advanced encryption and backup SD card recording on the belt pack. This is a useful feature in cases where the wearer momentarily goes out of range of the receiver as the recording can be retrieved afterwards from the card. Third party mic capsules are available and can offer a high quality alternative to those supplied with the transmitter and receiver.
Handheld Microphone
When conducting interviews it can sometimes be preferable to use a handheld microphone. They are particularly useful when a number of short interviews or ‘vox pops’ need to be conducted in quick succession. It avoids the need to mic interviewees up with a lav and also gives the presenter the control to prompt people when to speak by pointing the mic towards them for a response.
Handheld mics are usually dynamic, making them durable and capable of handling high sound pressure levels if required. They can have cardioid or omnidirectional polar patterns and are designed to minimise handling noise. Windshields can be added along with branded ‘flags’ with a channel name if required.
When very high background noise is present and a presenter or commentator needs to be heard over it, such as in live sports broadcasts, a handheld lip-ribbon mic is usually the most suitable choice. This type of microphone uses an acoustic baffle within the body of the microphone. This, combined with the mic’s bi-directional polar pattern, controls interference from background noise because sounds incident on the sides of the microphone are 180° out of phase with each other and so cancel out. Lip-ribbon mics typically have a frequency response which doesn’t extend much beyond 10kHz. This is usually fine for spoken voice and has become an accepted part of the commentary style.
Stereo Microphone
If you need to capture ambience or stereo wild track when out and about, the easiest option is to use a stereo microphone. Stereo mics usually have two coincident capsules in a single mic body arranged in an X/Y configuration. Some use a 5 pin XLR connector which can be used with a cable that splits into two standard mono XLRs for connection to an audio recorder or camera.
If you’re shooting B roll or stock footage and want a simple way to capture stereo atmos with each shot, mounting the microphone to the top of the camera and connecting it straight into the XLR inputs provides the most straightforward solution. A windshield is a good idea but be careful to ensure that this doesn’t become visible at the top of the shot if the microphone protrudes above the lens at the front of the camera. Be sure to check the rotation of the mic to ensure that left and right are pointing in the correct direction. Usually the model number is printed on top of the mic near the XLR connector so this can be used as a reference for whether or not the orientation of the microphone is correct, combined with the use of headphones of course!
Stereo microphones are generally not preferable for use on dialogue because this creates an image which shifts as the person moves. There may be situations where you deliberately want to do this for creative purposes but the vast majority of the time, dialogue is best recorded in mono and panned centrally in post.
Stereo microphones can also be useful as audience mics when filming small live shows or performance events. Coupled with the sound from on-stage performer microphones, the stereo mic can add the ambience and acoustic of the venue along with audience reaction and applause.
Studio Condenser Microphone
Our final choice in this list is the studio condenser mic. Sometimes you need to record narration or voiceover when out on a job, either on set or at a suitable available location. This can sometimes be due to time constraints or an actor/presenter’s limited availability. Keeping a good quality studio condenser mic in your filming kit provides you with the option to capture voiceover at a time that’s convenient for cast and crew on the occasions when a studio session isn’t possible.
In an ideal world, all narration and VO would be recorded in a proper studio with acoustic treatment and nice preamps but on lower budget productions or when a very quick turnaround is needed, this just isn’t possible and so the recording needs to be made on set or location. An additional piece of kit to consider for this purpose is a reflection filter. If you have the room in your kit bags for one of these, they’re a great way to mitigate the effect of room acoustics when recording voices with your condenser mic in less than ideal settings.
Final Thoughts
It’s evident from the information we’ve covered in this article that in order to be prepared for every eventuality when capturing sound on set or location, you’ll need a variety of different microphones. The exact one you choose of any given type is entirely down to your budget and specific requirements. We’ve included examples of each type for illustration but there are thousands available and so it’s impossible to narrow the list down to just a handful of specific models. What are your preferred mics to include in your filming kit? Let us know in the comments.
Top photo by Jonah De Oliveira on Unsplash