This is turning into a more technical blog than I initially thought but I had a look around the internet and could really find the information I was looking for! So here goes, the 7d's built in audio is pretty terrible and so i use a two system solution and the zoom h4n is the ideal tool for that heres a pic:
It records at great quality you can find all the specs here. It sounds great BUT and its a big but when you use phantom power which i do with my mics with average batteries i get around 6 min of battery life!!!
When i dont use the phantom power i get hours. This becomes a big issue when you can't plug in anywhere or your on location.
Also the sync with FCP is interesting. I use plural eyes which is a great tool to sync audio but settings wise you do need to be careful. Shooting at 24p i dont have a clue how to resync my audio as it drifts over the scene. So shooting at 25p it works ok. I think there is some sort of issue with FCP and audio sync so if anyone has any solutions please email me as how i have it set up at the moment, i shoot at 25p, record at 48k 16 bit (when i shot at 21 bit audio drifted). The other issue is that it is very difficult to ride audio levels when you are recording as it sits ontop of the camera and the controls for input levels are on the side and very trick to use if you have a shot gun mounted next to it.
So thats the moan out of the way. apart from that the clarity of audio is amazing. The price is incredible and it is very light and well made.
If anyone has a good work around for the level issue please email me as i am really keen to work out a solution as the kit is amazing!