omnidirectional polar pattern microphone and its use in film scenes:

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bowie_rascal

Member
i know its a round shape in polar pattern and it picks sound around it equally. but tell me in what type scene and situation we use this omnidirectional microphone?? i am still debating for this, anyway i am a film guy, so please don't give example for tv news or stage environment, lets only talk about film scenes and situations here. thankx in advance!
 
Omni lav mics are used in films where required.
My suggestion would be to use a qualified audio professional in your productions who knows when to use said mics rather than guessing or debating.
 
In everyday shooting you don't. The TV and stage experience, which you don't want to hear about are good grounding areas for the skills you need to deal with audio of any kind. There are times when an omni mic can be handy, but so much depends on the environment. Do you really want to hear all around? The muttering and script/sheet turns of the people behind the camera? Let's create some scenarios where omni miss could be useful. How about a couple of people just far enough apart to mean a single shotgun can't cover both of them, and you don't have two - but the shot is fairly tight so you can get an omni in close, between them, above or below the frame. Or maybe you have a huge battle scene - and you can hide a few omni miss in the middle of the action - or maybe you have a circular table with lots of people sitting around it and you need to hear everyone?

In all these cases, it's simply a microphone that can't let the wanted sound go-off axis. However, in most cases, doubling up on cardioids or shotguns works better - but so much depends on circumstances. I've got a Beyer M58 handheld, from my radio days, and omni capsules for some smaller miss - plus of course some labs. In most cases, I don't start with the omnis, but can pull them out of the case to solve problems.

The TV news and theatre people have a specific need for omni miss - but film, and general TV don't need them so much. I have a friend who loves M/S recording, and he actually likes an omni + fig-8 combo to give left and right in rooms he wants to sound bigger. I don't like the sound myself - it's a bit 'thin' to my ears, but he works a lot in churches and is convinced it's worthwhile.
 
The Reservoir Dogs clip is blocked in YouTube. The Godfather clip may have used an omni for those shots where everyone in the room is murmuring and reacting to a speech, but you can be sure that the dialog from individuals was NOT recorded with an omni. Even if the table were 1/10 that size and only 4 people around it, they would have to be in an anechoic chamber to make an omni microphone viable for recording dialog in a scripted production.

If an omnidirecitonal microphone were used 5% of the time for typical dialog recording in scripted productions I would be very surprised. Especially with more (most?) production happening in the Real World out on location (vs. a studio soundstage), I would think there would be vanishingly little use for omni microphones.

Now I do as much location music production (audio only) as video and even there I don't often have situations where omnis are the best choice. Again, it is usually a compromise between where I can put the microphone(s) and the acoustics of the venue, and I need to get as "clean" a recording as possible since there is no "take 2".

And even the Godfather murmuring shot was probably more likely to have been created synthetically from 42 tracks of custom-recorded "walla" sound skilfully mixed together by an experienced team. http://en.wikipedia.org/wiki/Walla

I just saw something a few days ago about creating the sound track for one of the big battle scenes in the Lord of the Rings trilogy. They had a team of three people just to create and mix the sounds of the arrows flying through the air. And another team creating and mixing the sounds of the arrows hitting targets (or not). The lesson of the story is that the more "natural" it seems the more likely there are dozens or scores of man-hours that went into creating the sounds from scratch.

But there are still SOME sounds that come from the actual shooting. I also just read a story about the research that went into discovering the optimal placement of a microphone on a horse in a cavalry battle to get enough of the hoves, the horse's breath and "voice", but minimizing the noise from the saddle, and other tack. They said it was halfway up the neck of the horse. Not sure how they hid them from the cameras other than keeping them on the far side. This was for the movie "War Horse".
http://www.soundandpictureonline.com/wp-content/issues/Sound_Picture/Winter2011/SP_Winter2011.pdf the cover story on page 26.
 
a scene where you have an actor or two speaking but you don't like the ambient sound you hearing behind. do u will record the background noise/ambient sound in "omni-directional microphone" alone as a separate track. so when you are ready to mix and edit the film, you can blend the two together and create the perfect mix that you want. is that true? because i got come across people advice me to record the ambient sound of any scene before start shooting. is that true to record the ambient sound u use "omni-directional microphone"?
 
Except for really zero-budget and home movies, the prime directive is to record the dialog as "clean" as possible. That means as little interference from environmental noise and ambient acoustics as humanly possible.

THEN whatever background noises are added in post-production (editing and mixing). For high-budget productions (Hollywood movies, prime-time TV, etc.) the background sounds are more likely selected out of a library or created on a Foley stage. Recording location background sounds may be done with an omnidirectional mic, but I suspect that most production sound mixers don't even carry omni mics in their everyday kits.

There is also the concept of "Room Tone" which seems to be what you are talking about. Room Tone is used during editing dialog to replace otherwise dead-silent gaps between words, phrases, etc.

Room Tone recordings should always be done with the same microphone (hypercardioid or shotgun) that the dialog was recorded with. Ideally, it should be done immediately before or after the shot, and with all the cast and crew frozen in their places. The reason is so that the sound will be as close as possible to EXACTLY the same as the dialog recording. But as you might imagine, this is usually difficult to do unless the director is particularly sound-conscious.
 
bowie_rascal said:
a scene where you have an actor or two speaking but you don't like the ambient sound you hearing behind. do u will record the background noise/ambient sound in "omni-directional microphone" alone as a separate track. so when you are ready to mix and edit the film, you can blend the two together and create the perfect mix that you want. is that true? because i got come across people advice me to record the ambient sound of any scene before start shooting. is that true to record the ambient sound u use "omni-directional microphone"?
Click to expand...

You might want to take a look through the sticky on post sound.

The only thing on a film with a budget that comes from the set is the dialog. Folks spend a lot of time cutting out anything that isn't dialog. The dialog editor may use some of that room tone to fill the holes made by cutting out non dialog bits but is not the mix.

Everything else is added in post including backgrounds.

To your original question. One might use an omni in a tricky position for a plant mic. It's not uncommon as a handheld interview mic. As mentioned many lavs are omni. Yu sometimes use one for FX recording. Maybe for doing Walla.

It's silliness to try and separate film, video, and music when talking about sound because there is way too much crossover. Films pretty much all have scores so music IS part of the film recording. There are video productions that are better than 90% of the films ever made and are recording the same way that they would on a film.
 
bowie_rascal said:
but tell me in what type scene and situation we use this omnidirectional microphone?? i am still debating for this, anyway i am a film guy, so please don't give example for tv news or stage environment, lets only talk about film scenes and situations here. thankx in advance!
Click to expand...

An omni mic has 3 essential characteristics:

1) does not reject sounds in any direction (obviously)
2) has no proximity effect
3) is required in using certain techniques to do stereo sound recording

Because of 1) and 2), this type of mics is popular in ENG-type interviews. That's because it allows you to capture spoken words loud and clear even in a very noisy environment, as long as you get close enough, without throwing away too many background sounds. The captured background sounds reinforce the fact that you were recording in a live environment, not in a studio or other type of staged setting.

Regardless of what purposes are served (filming, news gathering, stage recording, or else), the guiding physics of sound and the best practices of sound recording are always the same.

I don't think you have to use an omni mic to capture ambient sounds or "room tone". Which mic to use, whether to pick an omni mic, how to blend a take using this type of mic into the rest of your work, and so on, are all totally up to what you need to do given a particular scenario. Understanding acoustic characteristics of different mics as well as properly evaluating the acoustic properties of the recording environment are key to making the best decisions in sound recording.
 
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