In the world of video production, shotgun microphones are widely considered the go-to standard for getting the best audio. And, as most producers have learned, audio quality can make or break any film or video project. That’s why it’s important to choose the right microphone and to use it properly. Whether you’re shooting an amateur video or a professional video, a news report or a vlog, poor audio quality can lower the value of any project — even if it’s a visual masterpiece.
To get the best sound quality from your shotgun microphone, you need to first understand the basics of how it works.
What is a shotgun microphone?
Shotgun mics are long, narrow tubes with slits evenly spaced along each side and a capsule near the rear end. Also called interference tube microphones, these mics are designed to allow sound from in front of the microphone to pass through the tube to the capsule. At the same time, sounds from the sides must enter through the slits. This creates a phase cancellation effect that results in the rejection of those off-axis sounds.
In this way, these mics can pinpoint the source of sound while rejecting other noise. Some fans of shotguns have come to refer to them as ‘sniper mics’ because, when it comes to accuracy, there’s no substitute.
The exact design and quality vary between shotgun mics. Good ones can reject nearly all sounds coming from the sides while still picking up sounds from the front. These will give you a better signal-to-noise ratio.
Advantages of shotgun mics
Capturing high-quality audio offers many challenges when shooting video. One of the biggest advantages that shotgun mics have is their narrow pickup pattern. This is a big step up from your camcorder’s built-in mic, which generally has lower quality and a wider pickup pattern leading to more of the surrounding environment making it onto your recording. Built-in mics are generally not designed for quality audio. They can pick up a lot of background noise and wind, while shotgun mics give you clearer voice pickup.
One of the biggest advantages that shotgun mics have is their narrow pickup pattern.
Another advantage of shotgun mics is that they have a long reach. This helps tremendously when you have to record at a distance. Because their pickup patterns are long and narrow, these mics can often help isolate and records sound coming from farther away.
That being said, however, keep in mind that shotgun mics do not “zoom” in on sound the way a camera lens zooms in on actors. The most expensive shotgun mics can only capture audio from a distance of six to ten feet, while the less expensive ones only capture sound at a distance of three to four feet.
Shotgun mics vs. lavaliers
Shotgun mics and lavaliers (also known as lapel mics) can both capture quality audio when used properly. Both are great for dialogue, vlogging and interviews. Lavalier mics are generally clipped onto the subject, so even the omnidirectional variety can offer a good signal-to-noise ratio due to their proximity to the sound source.
Though there are directional lavs available, shotguns generally offer a tighter pickup pattern, and their form factor makes them considerably more versatile. Shotgun microphones can also sound more natural when you compare them to lavaliers, and you don’t need to hide them on actors to keep them out of your shots.
Properly positioning your shotgun mic for better sound
As we have discussed, shotgun mics focus closely on the subject directly in front of them, and they reject sounds from the sides and the rear. That’s why it’s key to get the microphone as close to your subject as possible and to keep it pointed directly at your sound source.
The best sound will come from positioning the shotgun mic a few feet above your subject. Booming from above the subject allows a more crisp and clear dialog to be heard. When booming from above, the microphone will be pointing downwards and the noise from around the room will be off-axis. This gives you more emphasis on the voice and less environmental noise.
Another positioning rule to follow is that, if you’re shooting indoors, try to avoid aiming your shotgun mic at hard surfaces. Think hardwood floors or brick walls. These surfaces reflect sound waves that cause the sound to be somewhat hollow and can reduce the effectiveness of the interference tube design. This means more noise will come through on your recording.
Get to know the mic before you buy
There are different mics out there and you have to know which ones work best for your shoots. You may be shooting an interview or doing a vlog, or you may be a field reporter on location. For each situation, there are various mics to accommodate your shoot. Understanding your mics allow you to use them more effectively.
Since most shotgun microphones are designed to pick up the human voice, frequency range will likely only be a concern when shopping for a mic to fit a particular use case. Keep in mind that longer shotgun mics are better at rejecting lower the off-axis frequencies.
Perhaps more influential in your purchasing decision will be the microphone’s pickup pattern. This determines how directional the microphone is. Omnidirectional microphones, for instance, capture sound from all directions. Cardioid mics capture sound from the front but don’t capture sound so well from the sides and reject sound at the rear.
There are several kinds of polar patterns for shotgun microphones:
- Supercardioid: a narrow pickup pattern where the microphone is sensitive right in front of the diaphragm and sounds off-axis are rejected
- Hypercardioids: like a supercardioid but with a more narrow pickup pattern and an extended rear pickup
- Ultracardioids: the most narrow pickup pattern possible, not usually good for use on a boom pole since they are so directional that the slightest move has the subject go off-axis
Any choice you make in buying a mic for your shoot should be based on the pickup pattern — the directions from which the mic captures the most sound. This is not written in stone since shoots and project requirements differ, but once you have a thorough understanding of pickup patterns, this should narrow down your choices.
Shotgun mic shortcomings
Though shotgun mics offer some great advantages, keep in mind that they can also offer challenges for certain shoots. They also normally require extra equipment. If you plan to have any movement during your shoot, you’ll need a boom pole and a special shock mount. And for outdoor shoots, expect to add the blimp or dead cat as mentioned earlier. In addition to that, your shoot will require an operator who knows how to keep shotgun mics out of your shots while still positioning the mic to get the best sound.
Shotguns are also particularly prone to wind noise. This is because of their open-back capsule design. Professionals suggest using what is known as sound blimps or a “dead cat” windshield. These are designed for minimizing wind noise when recording in high wind conditions. Some even suggest using these noise suppression tools even if you’re shooting indoors.
Additionally, shotgun mics aren’t the best choice for small rooms, especially those with lots of hard surfaces. They are more ideal for outdoors and large spaces with balanced acoustics.
If you’re seriously considering looking into buying a shotgun microphone, consider all of your options first. Your purchase should be based on the camera equipment you are using and on the project you plan on shooting. For some shoots, a lavalier or directional condenser mic may be a better option. Howver, if you want a versatile mic that can be used in a number of situations, a shotgun microphone is a better investment.