What to Know about Shotgun Microphones & Boom Microphones
Named for their shotgun barrel shape, shotgun microphones are considered the go-to solution for achieving focused, quality recordings of dialogue, foley, and sound effects in film, video, and TV productions, as well as for vlogs, web series, and even voice-over work. Why are they so popular? Due to their physical design principle, shotgun mics are able to pick up the source in front of them with a narrow, beam-like response pattern that greatly reduces ambient noise at the mic’s off-axis points (e.g. the sides and, to a certain extent, the rear). Though all shotgun mics share that basic characteristic, there are a myriad of shotgun microphones offering varied features for different workflows, applications, and users.
Camera-Mount Shotgun Mics
The smallest shotgun mics are usually made to sit atop a camera, which is why they’re often called “camera-mount” or “on-camera” shotgun mics. So, it makes sense that they would have camera-friendly 1/8” (3.5mm) TRS connectivity to plug directly into the mini-jack mic input of your DSLR/mirrorless camera or camcorder. Some include additional TRRS cables for hookup to smartphones and tablets, while others utilize auto-sensing circuitry to allow use with TRS or TRRS inputs without having to swap cables. Generally, camera-mount shotgun mics have short bodies to prevent them from creeping into your camera’s field of view, and the short length also helps keep them lightweight and easy to carry with a camera rig.
Traditional Shotgun and Boom Mics
Longer than their camera-mount counterparts, traditional shotgun mics are favored by boompole operators and sound recordists for their sharper directivity, more uniform off-axis rejection across the frequency spectrum, and increased sonic fidelity. So, why are traditional shotguns longer? The length of the mic’s interference tube—the ported or slotted barrel—directly impacts its effectiveness at rejecting off-axis sound at different frequencies; longer interference tubes yield greater and more consistent rejection. Since traditional shotgun mics are commonly equipped with low-noise electronics and balanced XLR outputs, they pair well with high-quality mic preamps.
Powering Your Shotgun Mic
Shotgun microphones use condenser capsules, which require some source of power. Most traditional shotgun mics need phantom power, though some may support battery powering. Some camera-mount shotgun mics run on batteries, others just need plug-in power from your camera, and a handful can operate via USB bus power. Mics that offer multiple powering modes let you choose between using batteries or phantom/plug-in power, allowing them to work with broader range of devices.
Additional Shotgun and Boom Mic Features
It’s not uncommon to encounter various switches and dials on shotgun mics. Such controls are incorporated to give you more power over the mic’s tone and level. For example, a low-cut filter (a.k.a. high-pass filter) rolls off bass frequencies where routine low-end issues such as rumble occur. A pad is useful for attenuating the signal level to avoid distorting when miking loud sound sources. Mics that have adjustable gain let you raise or lower the mic’s output level to optimize it for the input sensitivity of your camera or audio recorder.
Shotgun Microphone Accessories
Accessorizing your shotgun mic can enhance its performance and expand its versatility. Shockmounts have found widespread use because they impede the mic from picking up bumps and vibrations such as boom/camera handling noise.