Selection and Use of Shotgun Microphones

The other parameter by which we classify shotgun mics is by their pickup pattern.

Omnidirectional refers to hearing equally well in all directions. Most lavaliers are omni, which is good since they could end up being worn in different places and at different angles in order to accommodate clothing styles. Omni mics are also preferred for handheld interviews, since this allows for the unexpected overlapping of dialogue between interviewer and subject.

Cardioid pattern literally means heart shaped, and refers to microphones that are more directional from the front.

Hypercardioid or supercardioid are considerably directional. This group includes what are known as "short shotguns" such as the Audio Technica BP4073 and the Sennheiser MKH416/60.

Ultra-directional means extremely directional, such as full or long shotgun mics. Examples include the Audio Technica BP4071 and the Sennheiser MKH816/70.

So which mic to use?

The rule of thumb is that the more directional the microphone, the more it will emphasize echo in a small room. Therefore, reach the best compromise between the reach you need and the mellowness you would like to hear.

Long shotguns work the best for most exterior shots, since theses mics are characterized by long reach and very narrow pick-up. The narrow field of view helps to control background noise if the mic is deployed overhead. The greater range helps because exterior shots are very often much wider than interior frames, since there is more interesting stuff to look at or action to cover. Long shotguns can be successfully deployed up to 8 or 9 feet overhead, depending on the situation.

Always used a blimp windscreen on your long shotguns to guard against wind noise. I find that using a thin foam windscreen inside of the blimp (but still leaving some airspace) gives almost twice the protection. On the very sensitive condenser mics, a furry windsock will help to disperse the wind and diffuse it upon impact.

The new K-Tek Fuzzy windscreen is a mini-zeppelin with integral furry covering that fits over the mic like a foam windscreen, but offers adequate protection against light wind and is considerably less expensive than a full zeppelin rig.

To guard against rain, use lots of ScotchGuard spray. Extreme rain (or fire fighting) would call for a thin condom over the mic itself, as well as a rainhat over the blimp made from what we call "hogs hair" or "rubberized hair". Hogs hair is a thicket type material that will break up the raindrops and prevent the pitter patter sound of them striking the windscreen, roof of a vehicle, or roof of a recording stage.

Long shotguns may also be used on some interiors, providing that the room or sound stage is very large and free of echo. They offer the advantage of increased overhead range and headroom on wide shots. Their disadvantage on interiors is: 1) they are physically longer and may bump a low ceiling; 2) they must be precisely cued or aimed because of their narrow pattern (to cover two actors requires a very good boom operator); and 3) long shotguns will exaggerate room echo.

Prime examples of high quality, condenser long shotguns include the Audio Technica BP4071 and the Sennheiser MKH70. There are still a lot of the older MKH816's floating around.  For those on a smaller budget, the Audio Technica AT8015 and the Sennheiser K6/ME67 are ENG quality shotguns that can operate from an internal AA battery.

Interior locations are usually better off being miked with a short shotgun. The short shotgun features a slightly wider pattern and slightly less range, but does not exaggerate the room echo as much. The wider pattern and physically shorter length of theses mics facilitates use with lower ceilings, especially when it comes to covering multiple actors. Condenser short shotguns can be deployed indoors up to 5  feet above the actors (though 2 to 3 feet is better).

Today's favorite short shotgun condenser mics include the Audio Technica BP4073 and the Sennheiser MKH60.

In the choices of electret condenser short shotguns, there are the Audio Technica AT897,the AT8035 and the Sennheiser K6/ME66. Neither mic offers the range (4 to 6 feet) of their big brother condensers, but at shorter distances (up to 3 1/2 feet) they sound very good on the soundtrack. The main advantages of these ENG shotguns are price and ruggedness. Both mics are the standards of the news gathering industry.

Indoors, all short shotgun mics should always be used with a foam windscreen. Out of doors, a blimp windscreen or half-blimp such as the K-Tek Fuzzy Slip-On or Rycote Softie should be utilized.

In a pinch, simply wrap a few layers of cheesecloth over the foam windscreen, and then cover in a tube-style sweat sock. It works.

Any shotgun mic should always be used in a good shockmount to eliminate handling noise and vibration. The industry standards for short shotguns are the Audio Technica AT8415 universal shockmount (the tic tac toe rubber band mount) and the efficient K-Tek K-SM.

Blimp windscreens require their own brand of pistol grip shockmounts, which are usually purchased in conjunction with the windscreen system. These mounts are intended to be used with or without the windscreen, so there is no need to purchase a separate shockmount if you have a blimp system.

In addition to the long shotgun and short shotgun, Hollywood has begun using a third type of microphone in its quest for perfect dialogue. Some condenser cardioid microphones have become popular for their ability to reduce or even eliminate echo in a small room or set!

These mics yield a very rich voice track, are are favored for close-ups and medium close-ups where the overhead mic will not be more than two feet overhead. Examples include the Audio Technica AT4051b (pictured), the Sennheiser MKH40, and the Schoeps CMC4/MK41.

One last point. Make sure that the boom operator can HEAR the soundtrack! In order to properly position a mic both in terms of distance and angle, the boomperson must be able to listen to what is being picked up. Provide a headphone feed either via a wireless (assistive listening) rig or with a long headphone extension cable.

On professional sets, we uitilize a special mic cable (known as a "duplex cable" or "boom cable") that combines an XLR  microphone cable with a headphone cable in one housing. This cable conveys the audio signal from the mic to the mixing board while sending a headphone feed back to the boomperson.

Because there are often multiple mics in use on a set (boom, plant, lavalier, wireless) -- the boom operator should be monitoring the entire mix (not only the boom mic) so as to be aware of any phasing problems that would be created by two mics picking up the same actor at the same time.

This article was originally published by Student Filmmaker Magazine.