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Camera Mic On F900

Published : 2nd July 2004


I am in production on a documentary style shoot with the F900. All the locations are in hot climates. After experiencing a shutdown on the first shoot, we have resorted to running the fan full blast, and shielding it with an umbrella whenever possible. So now, under a lot of the audio, we can hear the fan humming in the background. I am using a Sennheiser shotgun mic...adjusted for a narrow range, but it still picks up the noise. We can clean up some of it in post, but that's not a good long-term solution.

Does anyone have any suggestions for getting around this noise (other than always using a sound-person with a boom, which is not always in our budget)?

Dan Fox



1) Put the camera fan back in AUTO it should go into whisper mode when recording in Auto Fan MAX will always be noiser.

2) Keep the camera in SAVE mode

3) Use a "Greeny" or "Tweaker" and open up the air intake vents on the bottom behind the shoulder pad a little wider.

4) Gaff tape the Camera white (you would be surprised)

5) Inspect the Fan that it has no obstructions or burrs making noise

6) At lunch open the sides up and cover with a camera blanket shiny side out this will cool it down quickly even in 99s weather high humidity. The camera generates 120s heat on its own and is very happy there.

7) If practical put the boom mic on a little flex rod 24 inches away from the camera. similar to what you would use for a French flag or a gooseneck. Every little bit helps.

8) If all else fails hire a sound guy to mic it with a boom properly and go to longer lenses to get the racket away from the action. Sound is either important or its not. if its important, do it right. If not then quit worrying about it.

B. Sean Fairburn SOC
HD DP LA



Dan Fox wrote :

>Does anyone have any suggestions for getting around this noise (other >than always using a sound-person with a boom...which is not always in >our budget)?

Try a Schoeps hypercardioid (MK41 capsule) in a shock mount, mounted from the camera but on an extension, so it ends up over the lens (i.e. the windscreen -- use a BD5) right at the end of the lens.

This mic is sensitive to handling noise and wind noise, so a proper shock mount (Schoeps makes one) and a proper windscreen are essential…but it's the best dialog mic out there.

You might need to add a cut-1 filter (from Schoeps) between the capsule and preamp if the fan noise is low-frequency.

But a soundman would be a better choice.

Jeff Kreines



>Does anyone have any suggestions for getting around this noise (other >than always using a sound-person with a boom...which is not always in >our budget)?

Following Jeff and Sean's good advice about reducing camera noise and getting the mic away from the camera, let me also concur a sound person is by far the best choice for just about any situation.

But what sort of sound are you trying to grab? man on street interviews? single host leading us through some ruins? football game? wildlife?

That'll help determine the best solution (other than hiring a sound person).

What Sennheiser mic are you using now? Perhaps a different pattern will help.

In addition to the Schoeps MK41, you might also try a Sanken CS-1. It's a very short shotgun that's a bit more directional than the 41. I've only used one a little bit, but it's quite nice and rejects off-axis noise more than say, the Schoeps or a Sennheiser 416. That's good for rejecting off-axis noise, bad for rejecting off-axis sound you do want. It also has good "reach."

http://sanken-mic.com/english/index.html

Are you shooting one or two people constantly? Have you considered using lav mics with radio systems? An inferior choice compared to a mic on a boom held by a good sound person (sense a theme? <g>), but it might work.

Anyway, more detail about what you're trying to do will help.

Jim Feeley

Edits words, records sounds, produces docs, writes grant applications, wants bigger budgets in San Francisco California.

Jim Feeley
POV Media
http://www.povmedia.com



I know a documentary maker who was suffering vibrational camera noise transmitted to his on-camera microphone. His solution was to take the mike off of the camera and tape it to his left shoulder. Said it worked surprisingly well although he looked silly and it was a big pain whenever he went to put down the camera.

Mitch Gross
NYC DP



Under less that ideal production conditions it would be best to record the audio signal "as is" and then manipulate the sound in post with notch / equalizing / other filters to remove the fan noise -or- as you've already heard, use a sound person with boom mic.

Having said that I learned a lot from Jerry Bruck, who, as Posthorn Recording, is a distributor of Scheops microphones as well an excellent audio recordist. Another option Jerry shared with me a while ago might be to test placing a second "matching microphone" as an "ambient" pick up device (i.e. not directly next to the on board mic) and then from this mic go into the other camera audio input with a phase reversing cable (pin 1-1, 2-3, 3-2 I believe) on that channel which then will serve to "phase out" many similar audio elements of both channels -- hopefully the fan noise. To hear if this is working on location you must be able to monitor the audio in stereo -- not left or right channel but both simultaneously. And this "phase reverse" method will ultimately affect the audio fidelity quality overall.

Bob Zahn
BVR, New York



Bob Zahn wrote :

>Another option Jerry shared with me a while ago might be to test >placing a second "matching microphone" as an "ambient" pick up >device etc.

Trying to do that on location with camera moves respectively subjects moving around would be quite a disaster, not to mention that one now has to deal with 2 microphones. Definitely not working.

I can somehow understand not having the budget for sound when shooting miniDV, but shooting HD and scrimping on sound doesn't make mucho sense to me - somewhat unbalanced. One of the issues that comes up when choosing a camera mounted mic is the 'directivity' of the microphone. While a 'shotgun' blends out noise/unwanted sound from off axis sound sources entering/exiting might sound a bit artificial. This is less so with hyper-cardiods obviously, but having a broader sound field now of course it will pick up more unwanted sound signals.

I also want to add that there are other excellent microphones in the same league as the mentioned Schoeps like the Sennheiser MKH50 or the AKG 480/ck63 or the Neumann 150.

Karl Lohninger
DS (directeur du son)
Location sound, sound editing, etc.
Los Angeles



Dan Fox writes :

>we have resorted to running the fan full blast, and shielding it with an >umbrella whenever possible. So now, under a lot of the audio, we can >hear the fan humming in the background.

Here's what I just wrote to Robert Rouveroy in cml-video :

>What works best for me is to shockmount a short shotgun (Sennheiser K3/ME80 on a multi-jointed bracket that lifts the mic up and forward about eight inches. That keeps it out of frame and away from the tape mechanism, and closer to the subject. With this rig (at maximum bass cut) I can shoot wide-angle exterior interviews with sound that rivals or exceeds good Lavalier sound. I only have to be careful to avoid panning or arcing around to where sources of noise come into the sound "frame.">>>

Sean Fairburn writes :

>4) Gaff tape the Camera white (you would be surprised)

What do you mean by this?

>Put the boom mic on a little flex rod 24 inches away from the camera. >Similar to what you would use for a French flag or a gooseneck. Every >little bit helps.

A flex rod is fine if it's stable enough. Just make sure you're monitoring your video under scanned, and check every so often that your mic is well clear of your widest framing and not encroaching incrementally every time you bump the camera. 24 inches may be a bit much, but try it and see if it's practical. You can also try extending the mic from underneath the camera -- which means that if your mount loosens up the mic will fall AWAY from your frame.

Most importantly, make sure you're monitoring your audio critically with good headphones (i.e., Sony MDR-7506). This may take a bit of practice, since these closed-housing phones tend to isolate your hearing from the natural environment. But without that isolation you won't really know what you're getting.

Dan Drasin
Producer/DP
Marin County, CA



Bob Zahn writes :

>Under less that ideal production conditions it would be best to record >the audio signal "as is" and then manipulate the sound in post with >notch / equalizing / other filters to remove the fan noise -or- as you've >already heard, use a sound person with boom mic.

You'll usually end up processing in post anyway -- but "as-is" can mean many things, depending on how the original sound was miked and monitored. As with video there's no substitute for an original track that's as clean as possible. Miking is, in its own way, no less an art and science than cinematography, and cinematographers need to respect that fact.

While you can fix a lot in post, there are limits...and the end result will never be as good -- nor will you be left with as many options -- as what you'd have with a clean original track.

>>Another option Jerry shared with me a while ago might be to test placing a second "matching microphone" as an "ambient" pickup device (i.e. not directly next to the on board mic) and then from this mic go into the other camera audio input with a phase reversing cable<<

With this approach there are also reasons to keep your original tracks in-phase, and do any phase reversals in post.

>>To hear if this is working on location you must be able to monitor the audio in stereo -- not left or right channel but both simultaneously.<<

Stereo won't quite do it. What you need is to be able to feed both left and right signals into a MONO L+R mix, which will enable you to hear the actual effect of your phase cancellations. When you monitor in straight stereo your brain will circumvent the phase reversals and overcome your intended noise cancellation.

Ideally you should be able to switch the phase in one channel (either will do) of your inputs or monitor mix BEFORE the left and right channels are mixed. This way you can do an A-B comparison of the straight and phase-cancelled sound, to determine which works best.

Even more important would be the types of mics used, and their relative placements. For example, if you mix the outputs of cardioid (directional) and an omni (non directional) mic, you're likely to experience what's known as "comb-filtering" where certain frequencies will cancel each other, but others will REINFORCE each other.

>>And this "phase reverse" method will ultimately affect the audio fidelity quality overall.<<

Absolutely. At worst it can sound hollow, watery, swishy, etc.

Dan "of sound mind" Drasin
Producer/DP
Marin County, CA