I have 2 cameras with on-board microphones (Nikon D5100, Canon Powershot G7), and I'm predictably having problems with high wind noise, and when recording short clips at gigs (with permission) with very high audio levels. Does anyone know how I could generally reduce the overall audio level? I've considered sticking felt tabs over the mic cover but this I feel is not the way to do it.
I suspect that I'll end up recording the audio on another device, but this is yet another thing to carry, and go wrong, so, advice please!
It would be best to use an external mic that can be positioned where less wind would strike it. A hand-held recorder, like the Zoom H1 recorder (under $100.00) would be an affordable choice for most people. Hand-held recorders have built-in microphones and also a jack for using an external mic. These recorders have adjustable record levels that can be set for best results (most cameras don't have this feature).
Whenever recording in windy conditions, you should cover your mic with a good fur windscreen.
www.thewindcutter.com can supply you with windscreens for any external microphone. We also have highly effective WindJackets for hand-held recorders. For your cameras built-in mic, we have Stick-On WindCutters.
You can't repair wind noise after the recording is done. I actually have a Kickstarter page for a product I'm making designed to solve this problem, using the same faux-fur principles as "dead cat" noise suppressors but for small microphones. I think it would help a lot.