Camera motor noise, my solution

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Alan Roberts at work
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Joined: May 6 1999

I sometimes use an external mic with my DX100, and get the noise of the camera motors into it by direct conduction if I use the shoe mount. So I've been experimenting with alternative mounts.

I've now made one that works. Total cost 21p and about 1 hour's work using bits I found in my garage.

Materials:
Soft black foam as found in camera rigid cases, about 2 square inches about 3 mm thick.
Piece of plastic (or even mdf) the same size, 8-10mm thick.
Piece of thin plastic, same size (actually a piece of glass fibre pcb material, unused).
Accessory shoe from a disused piece of photo kit (in my case a bracket with 3 of them on it, no longer needed).
Superglue.
Spring clip to suit (that's what cost me 21p).

I made a foam sandwich with the thick and thin layers, held together with superglue, about 25 by 50 mm. The accessory shoe is glued to the thin layer at one end (on top), any orientation that suits. The spring clip is fixed to the thick layer, so that it will hold the entire sandwich horizontal, when clipped to a vertical tube/rod (in my case, the front rod of my Hague stabiliser). And that's it.

The theory is that the motor noise is all rather low frequency, so we need a lossy coupling between the camera and the mic. The black foam is incredibly lossy at low frequencies (squeeze it and let go, it can take a second to get back to shape) but is nearly rigid at high frequencies (several kHz), just what we need. A thin layer is needed because it has to support the weight of the mic in the shoe, and that will be cantilevered, that's why the platform isn't square. It's also why the layer isn't thick. Do some experiments before committing to manufacture, I tried three variants of foam before I found the best. Simply put the camera on a hard surface, switch on with the mic connected, put the foam on top (anywhere will do), and lightly hold the mic onto it. Listen to it on cans and see if the motor noise comes through. Keep experimenting until the noise doesn't come through, then get gluing.

So, I clip the doings onto the front pillar of the Hague, put the Sennheiser MK300 into the shoe, plug in, and off we go. No motor noise. QED.

Hope that helps someone.

[This message has been edited by Alan Roberts at work (edited 16 February 2001).]

tom hardwick
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Joined: Apr 8 1999

Excellent practical advice AR@W. I fear many people simply buy a posh mic, slide it into the hot (or cold) shoe, and are horribly dissapointed by the performance vs the inbuilt mics.

tom.

Alan Roberts at work
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Joined: May 6 1999

Thanks Tom.

Upgrade #1:

From the bottom of the disused bracket, I removed the shoe plate, and attached it to the new adaptor by drilling right through and screwing it on (to the thick base plate). So now I can put it on the camera shoe and use the mic on top as well. On the whole, I still prefer to use it clipped to the vertical pole of the Hague stabiliser because it lets me reduce the counterweights a little. And it adds real distance from the camera which helsp quite a bit (less lens motor noise).