How To Shoot Better Videos With Your DSLR 2 of 3

So yesterday we talked about setting your camera to shoot video. Today we get a little more complicated. Let's chat about audio. Tomorrow we will take it one step further and discuss the most dreaded part of video... editing! If you have a Canon camera that shoots video, view the full post to check out a video on audio made just for you. We are slowly turning all of you photographers into videographers; you'll thank us later... or you could thank us now in the comment box below .

Do you shoot Canon? Check this out:

If Youtube refuses to load quickly (an issue we always have) Check out the same video on Vimeo below.

Untitled from FStoppers on Vimeo.

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9 Comments

Hey guys I'm digging the website, lots of great information.

Audio is always seems to be the forgotten step-child of the production. I've been doing video for about a year now however I am not an audio engineer and I am writing purely from experience.

I have a few things that I'm concerned about with what you've brought up here, though.

There are two parts to every audio system: The Microphone and the Audio Recording device. When you say that you get better audio from your iPhone than your sennheiser set-ups, I'm afraid that might be misleading to some viewers.

Sennheiser is a brand known for their quality microphones. The problem is that you were probably recording the audio through your D90/300s. Nikon and Canon both have a feature called Auto Gain Control (AGC). AGC will take the audio signal and bump it to whatever levels it deems are appropriate and will automatically attenuate any sounds that are too loud. While this is great for beginners and amateurs so they don't have to be constantly watching their audio levels, it becomes a problem for anyone wanting super clean audio. Using an external recording device such as the Zoom H4n allows you to manually control and monitor your audio levels and provides a cleaner audio file.

About the settings for you lav mics, I have a theory. Again, I'm not an audio engineer and if its working for you, great, keep it up. Setting the mics to -20 to -18db seems to be a little unnerving for me. Most conversational pieces should be recorded between -12 and -6db in order to ensure the highest quality sound while still allowing room for inflection. It seems to me that setting your mics at -20db would cause your camera's AGC to artificially bump your audio creating hiss and noise.

Finally I have done some semi-controlled tests using the D300s's audio features. I figure this would be a good place to post the results. I set my sennheiser MKE400 (connected to my D300s) on a boom stand between my computer's speakers. I played the same portion of a movie for each test that included normal dialogue as well as loud noises and quiet background (all separate). Here is what I found:

Setting:
Lo(1) - most sound recorded between -18>-12db, peaks at -6
Med(2) - most sound recorded between -12>-6db, peaks at 0
Hi(3) - most sound recorded between -6>0, peaks attenuated to 0
Auto(A) - most sound recorded between -12>-6db, peaks at 0
Audible hiss was similar across all settings.

In this situation Med(2) and Auto(A) seem to be the same, however I have a feeling that is because of the controlled situation. Auto will most likely bump less audible sounds more than medium in a more real-world situation.

I hope that what I've written makes sense, and if I'm incorrect about anything please feel free to let me know. I've only been doing this for about a year and am still learning.

-mike

Patrick Hall's picture

Mike, I think you nailed it on the head about the AGC affecting the quality of our audio. The way we went about testing for our particular setup was we placed the lav mic about 2-3 buttons down on a typical shirt (around lower breast to collar bone) and checked the levels on the mic unit. We aimed to keep the LCD level around 2/3 of the way up so it wasn't spiking but it was getting a good solid signal. This was pretty much a control but we did try other variations (this setting was -20db). Since we assumed a spike of 2/3rds on the mic's level line was a good input level, we then tested every combination of Camera Setting and AF Out on the receiver unit. If -20db was the best input of the mic, we found that the best fullest sound came out of Camera Low and Receiver at -18db.

We then tried more combinations of increasing the camera setting while decreasing the AF out on the receiver. Every single setting we tried that was not Auto or Low on the camera produced horrible distortion. I even tried using a cheap computer mic straight into the camera to remove the Sennheiser variable and again every recording from Mid or High produced horrible static and was not usable.

<em>Could our mic level problem be that the LED signal should not be 2/3rds of the way up but rather actually hitting the right hand side of the levels?</em> We have been treating that spectrum like we would a Histogram where ideally you would not have any data hitting the far right side but as close as possible.

Also, we figured a way to make the camera less automated was to use anything besides the Auto Audio Setting. Are the High, Med, and Low settings not closer to the controls an external recorder would give you (they should be constant at least)? I really wish Nikon would give us more options in the Audio menu through firmware. I know the canon guys are able to replace the firmware to accomplish better audio recording; that sure would be nice on these cameras.

I can't wait for the third video in this series! Great stuff, guys!

Larry Sanders's picture

make sure you clap?

Lee Morris's picture

So you have a quick sound to sync the audio

Like I mentioned, I haven't had a chance to test the mic input levels in the camera in a "real world" situation.

The next test I'll do is to set the input to one of the non-auto presets and and more-or-less yell into the mic. I would expect to see that in Auto, the levels would be attenuated so it doesn't peak above 0 (thus causing distortion).

In medium, high, or low, I would expect the camera to allow the levels to clip themselves and distort. But then again, I also kinda expected the D300s to have fully manual video controls (like Canon) when if first came out... ;)

Patrick Hall's picture

Definitely let me know what you find. I just plugged the mic straight into the camera for a shotgun/better than on camera mic setup. The recordings I made in Auto sure did not sound like it was attenuated at all....it seems just like either Low or Med I forget but it isn't like constantly adjusting like you would assume. Let me know what you find.

I'd like to suggest a better way to attain a superior sound.

A JuicedLink Pre-Amp:
http://www.juicedlink.com/index_files/CX_camcorder_XLR_microphone_adapte...

With a Boostaroo Splitter To Monitor Sound.
http://www.boostaroo.com/store_detail.php4?id=123

For those whom don't have a D300s and need to fool the AGC they have a DN101.

Its been working wonders for me.

hi guys,
love the site. just wondering if you could publish your settings for your
transmitter
receiver
d300s mic settings

i just got the ew100 g3 and trying to get the right settings.

thanks!