Shotgun mic is a directional mic that must be directly pointed at the target sound to get high quality audio. It uses unidirectional capsule and is sensitive to the sounds in the front. However, when the sound source moves to the sides or rear, it captures lower sounds. You may find long or short shotgun mic on the market and wonder what are their differences. In this article, we will dive into this topic and help you pick the one that suits your recording requirements.
Key difference in length of interference tube
Generally speaking, short shotgun mic for DSLR differs from the long shotgun by the length of interference tube. The longer the interference tube is, the more directionality it has.
What is interference tube? In shotgun mic, an interference tube is an elongated acoustic labyrinth that produces the lobar polar pattern. It allows on-axis sounds to pass through unobstructed to the mic diaphragm while forcing off-axis sounds to cancel out as they pass through with different degrees of phase shift. The interference tube runs from immediately before the first slot (at the microphone capsule) to the top of the microphone.
Therefore, how does it work? On-axis sound waves can enter an interference tube from the top like a typical microphone grille, and they can then go directly to the diaphragm. In other words, there are almost no problems with sound traveling toward the shotgun mic from the direction the mike is pointed. The microphone is now sensitive to on-axis noises.
The interference tube's side slots handle sound waves in various ways. Off-axis sound waves enter the interference tube, where they are exposed to internal reflections and phase cancellation with surrounding sound waves.
Compared to sound waves arriving from the sides and those coming from behind the microphone, sound waves originating from slightly off-axis directions are less susceptible to destructive interference.
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Short shotgun mic vs long: Differences in uses
Long shotgun mic works well for exterior filmmaking. It offers the best reach and a very narrow pattern. It can operate both indoors and outdoors at 9 feet overhead or even beyond if it is not too loud.
The best side rejection is found in long shotguns, which is crucial for fighting background noise from the outdoors. They work effectively when placed 2 to 3 feet closer to the performers, when they are significantly more effective.
When employing long shotguns indoors, accuracy is essential. The actor will audibly sound off mike if the boom operator's aim is even slightly wrong.
Short shotgun mic, which is incredibly popular for newscasting, documentaries, corporate films, and low-budget projects, is the best option for professional productions.
Short shotgun microphones have an extremely directed pattern. They have a far wider field of fire than standard handheld microphones. These specific microphones perform best at a height of 2 to 3 feet, with no more than 3 12 or 4 feet overhead. The talent will begin to sound thinner and more ambient as the microphone is raised.
The mini shotgun microphone for camcorder is widely used and is frequently placed on cameras. Because of its compact size, it is both sturdy and portable. Despite being a short shotgun microphone, it is more directed and accurate than lavalier mics. It has a range of 4 feet. However, for optimal audio, place it 2 feet away from the subject.
Because of these properties, this shotgun microphone is suitable for interview, vlogging, video conference, interview, and other circumstances requiring a portable but directional microphone. It is the finest shotgun microphone for smartphones and other mobile devices in most instances.
Which length should you use?
It depends. The most off-axis sound will be rejected by an interference tube that is longer than it is, but that interference tube will be more challenging to deal with. Since moving the mic even slightly off-axis can cause the sound source to be attenuated, it is very sensitive to location and requires a fixed mic/source or a professional boom operator. This is frequently the best choice for very far-off noises and/or noisy situations. Most of the time, a medium shotgun is ideal for booming and voice pickup. Although a short shotgun is less directional than its longer siblings, it is nevertheless more effective than a hypercardioid microphone in rejecting high frequencies that are off-axis.
As essential as the degree of rejection is the kind of rejection. Even a shotgun with a high degree of directionality will allow off-axis sound at some frequencies. Your final product will suffer if this audio has comb-filtering anomalies in it.
The majority of shotgun microphones do a decent job of recording on-axis audio, but to get the best short shotgun mic, it's crucial to seek for low internal noise, high sensitivity, a natural on-axis sound, and consistent off-axis rejection. Overall, the audio will be at its finest with this.