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Old November 19th, 2010, 12:45 PM   #1
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HMC40 - audio upgrade?

I'm using my HMC40 with a Rode videomic to capture passing trains. I really like to get decent audio even when I'm at full zoom, so I have been setting the manual settings for audio in the camera at maximum (+6).
However this gets totally distorted when a train passes by only a few feet away, so I have been manually adjusting the audio levels down using the touchscreen as the train approaches, then running them back up as the train goes further away. However this method makes for definite "steps" in the audio which are very noticeable. I have adjusted for this during editing, but I was wondering if there might be a better way to do this, possibly with adjusting wheels so that I can make the reductions and increases smoother.
Also, on a different note, when filming at full zoom, my tripod head (701HDV) tends to want to "jump" in steps at first rather than moving smoothly. Any suggestions on a better head? Thanks
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Old November 19th, 2010, 02:21 PM   #2
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Hi Scott, and welcome to the forum!

I'm in the same boat... er, train as you!

Couple of things. For audio, I have the AG-MYA30G XLR Adapter and use an Audio Technical AT875R shotgun mic or a Rode NTG-1.

How does this help? Well, I only use one mic, normally. I know the purists say you have to get the mic within feet of the subject, but a great big noisy steam train can be heard more than a few feet away! So I use the XLR unit and switch it to feed the mic into both both channels, left and right. I can then use the level dials to have left and right channels at different levels.

So the left audio channel is recording at a lower level than the right channel. I can then choose which track I want to use in post, or even blend the two together, so if the right channel clips when the train is close and loud, the left channel is at a much lower level, and is not clipped.

I hope that makes sense! It works for me. I'll admit it involves spending money, which may not be what you want to hear, and there maybe a way to do it with the Rode Videomic, but I've never used it. If anything, I would suggest having the level generally low to boost it in post. Also check out the mic attentuation switches on the Videomic which may help you limit clipping.

Regarding the jerking. Is your Optical Image Stabiliser turned off? I use an 501HDV at the moment, and it's OK - not as good as my Sachtler was - but if I don't turn off the OIS it will jerk during a pan as the camera tries to smooth the movement. OIS is designed for handheld work only, really.

As an aside, my first field trip with the HMC was a fun time, I spent most of the day vainly trying to find the OIS settings in the menus. When I got home, I noticed the nice big OIS button on the side of the camera...

For smooth moves at full zoom, a better head and legs really are needed. How much better you get depends on your budget, and is best asked in the tripods forum.
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Old November 19th, 2010, 02:34 PM   #3
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Thanks Mike, for the great info. I had no idea I could use each audio channel independently, if I bought the xlr unit. That is exactly what I am going to do. And I will try turning off OIS too. Hadn't thought of that either.
Great info Mike. I'll keep you updated. Scott
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Old November 19th, 2010, 02:46 PM   #4
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Glad to help, Scott.

The XLR unit came either free or at a bargain price here in the UK. As a stopgap, you may be able to plug the Rode Videomic (via their simple adapter) into one channel and use the XLR unit as you would with an XLR shotgun.

Adapter here: RØDE Microphones - VXLR

Failing that, you could sell the videomic. The AT875R mic is very popular amongst HMC owners due to its small size, excellent performance and relatively low cost. I've added a Rycote windshield to mine, as steam trains always seem to appear on windy days here!

Update: attached a (not very good) photo of the set-up. Boy do I need to clean my camera!
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HMC40 - audio upgrade?-p1020779.jpg  
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Old November 20th, 2010, 06:30 AM   #5
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If you haven't already tried AGC, in the category of spending zero, AGC (Automatic Gain Control) on the audio is made for this kind of thing. It will adjust the mic gain. Granted, it's not ideal and your long shot audio may be "airy". The XLR audio adapter may have a setting that sends a single channel to both inputs. Alternatively, the technique of recording a single mic at two different levels is commonly done with a field mixer. A field mixer also gives you a decent knob and meter for manual adjustments.
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Old November 20th, 2010, 07:07 AM   #6
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I can confirm that the XLR unit does allow you to record one XLR mono signal and duplicate it to both channels, and definitely can allow you to record at different levels on each channel, without the need for any additional leads or adapters.

It's not in the same league as a field mixer (+ dedicated recorder), but for a one-man band with a tiny camera, the XLR unit on the HMC40/41 is excellent for this sort of thing.
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Old November 24th, 2010, 01:30 AM   #7
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Hi Mike

I really never liked the "curly cord" on my Rode VideoMics so I just opened up the mic and soldered in a length of decent quality screen cable and then added the XLR plug on the end. Now I have tough durable cable that doesn't need to be stretched and I know I won't have any audio issues either.

The VideoMic can be a little "hot" but my XLR panel on the HMC72 allows me to switch a 20db attenuator in and out so I tend to use the mic internal switches at 0db and then switch in the attenuator where needed. The ALC on the Panasonics does a fairly good job but the audio via a Rode will easily blow out with a train at close range!!! I'm not sure at what level the HMC clamp the audio at but the older prosumer cams used to be able to only handle up to +8db automatically.

If Scott knows that the next shoot might be a train passing quite close, an easy trick is to turn the entire mic assembly around 180 degrees (so it's facing backwards) and the reflected sound is often more than good enough!! I was doing a wedding on Saturday with a 3 piece strings band and a loud singer...the Rode on my A-Cam had the sound blow out totally BUT I was filming the bride arriving with the second camera with the music behind me and the camera, and the end result was perfect!!! I just used the audio from Cam B on Cam A's footage!!!

Chris
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