I've used a Beyerdynamic M 58 ENG interview microphone on a shoot with the FS100, but the audio level was very low. I had to set the audio levels to (almost) max, to at least get some audio from it.

Can anyone recommend me a better interview microphone for the FS100?

That is a dynamic mic and needs a different mic trim than an electret mic (the stock mic).

Check out page 36 of the FS100 manual to see how to change the mic trim in the menu.

Thanks Chris, will have a look at it!

Look out for the Triton Audio 'FEThead' microphone pre-amplifier:

FetHead - tritonaudio (http://www.tritonaudio.com/index.php?option=com_content&task=category&sectionid=4&id=17&Itemid=33)

Basically, you plug it into the mic input, it gets power from the camera's Phantom Power, and this drives a relatively high quality amplifier that cleanly raises your microphone level by +18dB.

Of course, dynamic mics don't requrie phantom power, but because they generate their own juice - at low level as you've discovered - they need a little help. But not all 'microphone pre-amplifiers' are built the same. I love my Sound Devices stuff now, but the FEThead helped a lot before.

That's a great tip Matt. Seems like a very handy amplifier!

I looked at the manual and was able to boost the mic level to +12 and that was enough to get proper sound from it! So, problem solved. :) Thanks for the help guys.

Just remember to set it back before plugging in a "hot" mic. Otherwise you'll have a ton of distortion.

Glad we could help.