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St Petersburg, RU
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"RE: External Mic for D4...long post"

km6xz Moderator Awarded for his in-depth knowledge in various areas, including Portraits and Urban Photography Nikonian since 22nd Jan 2009
Mon 01-Apr-13 10:36 PM

Hi Ned
I might be late with a comment but for your use, a small recorder such as the Zoom H4 which can be placed near your sound source, will keep your hardware requirements compact, inexpensive and very flexible. As Martin said, getting a sound pickup position that is close has many advantages over distance micing which is often a frustratingly futile endeavor. Shotgun mics and other highly directional mics are not for primary sound at a distance, contrary to popular opinion, but can be used for ambience sounds which do not convey information. Crowd noise for example is a good use of a distance mic technique but would never do for primary content of speech or music. Although sold as a distance micing solution to casual shooters, shotgun mics do not fill that role well at all. Nothing does. A shotgun mic is not selected for distance "reach", it is selected by the recordist for its highly directional polar response such as using in broadcast of stage events with a live audience. The shotgun mic is boomed right over the talent, just out of camera view on tight shots to improve signal to ambient sound ratio.
So in your case, consider methods of getting the mic very near the source, within 30 feet to avoid syncing problems since viewers are sensitive to image/sound lack of sync at and time differences greater than about 30 milliseconds. The images will lead the sound by about 1100 feet per second sound speed from the point of pickup. A mic mounted on the camera at a greater distance will always be out of sync with the image unless slipped in post processing solely due to the speed of light versus sound. A foot away from the source is better than 2 feet, and over 8 feet might be too far no matter what the acoustic space is like. But there are ways of getting 10-15 feet to sound good.
Placing a small recorder in the middle of the sound sources of interest in a scene helps in many ways to improve the quality of the sound. The most obvious is increasing the direct sound to reflected reverberant field ratio. Even 3-4 feet away from a source will start to degrade in intelligibility as the ratio of sound coming directly from the source starts to be overtaken by the many paths of reflected sound from that same source. This is particularly a problem indoors but also is a consideration when micing a scene outdoors in open space, with the main reflection path is the first reflection from the ground. The brain tries to filter out reflections and reverberation fields when the direct sound and delayed sound are both received by the ears as long as the delayed version of the direct sound is of a naturally occurring time and character relation to each other. We still "hear" the delay sounds and field but our brains filter it from our consciousness. When the delay become too long or too strong, the brain can't decide if the delayed sounds are related to the direct sound so assumes it is a new sound and we become aware of it. In recording sound, that filtration does not occur, the mic is not intelligent enough to be selective in what is picks up and records. So playing back a clip sounded perfectly normal and clean when in the room with your own ears might be unintelligible when pickup by a mic and recorded and played back. The mic is capturing what is really there that we just are not aware of in a normal acoustic space. Keeping that simple concept in mind, that any reflected sounds or reverberation fields will be competing with desired sounds in the recording. Getting closer with a mic is needed to get the same perceived ratio of ambient field sounds to direct sounds that we are aware of when there live.
By not knowing this, many people claim camera mounted mics are poor quality since playback reveals echo'y, reverb, bottom of a rain barrel sound that we did not hear at the time the sound was recorded. But in reality, the camera mic's problem was that it recorded what was really there. To make it sound good we much make sure the mic is in a much better position than our ears need to be for a similar perceived sound after our brains get finished filtering related delayed versions of the direct sound out of our consciousness.
Mic placement is a key to good sound. If you know where the source will be it is not hard to place the mic/recorder in a good spot, such as on the ground in the middle of a group of people whose voices are going to be the content. That way the first early reflection from the ground itself will be delayed only a few hundred microseconds instead of 8-12 milliseconds if placed at head level. When you control the position acoustic space, really good sound can be recorded even with modest microphones. After a little experience you should be able to intuitively pick the optimum place and in what orientation, for getting the best sound just by looking at the space the sound is originating from. It is the same sort of skill that serves a photographer so well when being able to instantly judge the tone range of a scene.
For a travel kit I would take a wireless link, adaptor cables, a small digital recorder, a few small wind protection items like a loose knit wool sock, or small ball of dacron that can be shaped into a air movement filter, gaffer's tape, a few bungee cords and pressure zone mic, a hypercardioid mic( or a low cost switchable polar response mic for omni, figure 8 and unidirectional), a cheap lapel mic with some clips and if space permits, a fish pole and some damping material to use as GoBos to control approach angle of the sound waves.
A big advantage of a portable recorder like the Zoom H4 besides its excellent performance and low cost is the long recording time. This means a continuous audio track can be laid down and any assortment of clips, stills and B rolls can be assembled for the visuals while having a full audio track even when moving the shooting angle or position, or using two cameras like when doing close in interviews, one on the questioner and the other camera on the respondent where cuts can be made between cameras at any time while maintaining the same continuous sonic content and sound character. Moving a camera mounted mic even a little changes the sound character which is really hard to maintain continuity of sound character between visual cuts.
You can get real pro level sound by thinking about it and acting on simple logical options without spending much money or taking more than a pound or two of gear. Good sound comes from good techniques appropriate for the session, not expensive high end equipment. The cheapest cell phone mic will sound better than the high end $12,000 mics any day if the $0.40 cell phone electret mic is placed optimumly and the high end mic is placed badly. I am often asked what mic to get or which mic I used on some record they are trying to emulate and I have a hard time giving the answer they want. They want a simple product model number to get that sound they liked. But the mic was not selected because of the mic being good, it was selected to solve a problem that involved the unique combinations of characteristics of the song, the singer, the acoustic space, and the goal. There is no best mic, only most appropriate for that unique combination of traits that might never be needed again. Is the same as when a beginning photographer asks what lens and camera was used on some noteworthy print on the gallery wall. The answer is not going to give the questioner any useful information that will translate to his upcoming session where all the factors are different than the session he is trying to emulate. In my case, my mic locker was filled with 250 mics worth from $1 to $20,000 a pair, and over 60 classic vacuum tube mics that are held in very high esteem by almost everyone. Visitors to the studio wanted to know about the expensive high end mics assuming those were used on records they liked but it would be shocking to them to know that some of those sessions, the most appropriate mic was a mic worth no more than $3. There is no "best mic".
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A topic tagged as in need of help External Mic for D4 [View all] , Ned_L Moderator Awarded for his in-depth knowledge in various areas, especially Travel Photography , Thu 21-Mar-13 11:58 PM
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