I am preparing to shoot a documentary using a Panasonic DVX100B. Most of the audio will be gathered outside, being that we are following a young man walking from LA to DC. My turmoil is will the audio captured straight onto tape be sufficient using boom and lavaliere or should I capture the audio externally with some kind of field mixer? There is a budget, and a field mixer was not figured into that, but I may just get one if that is the general concensus. I am not a sound man, and not familiar with exactly how field mixing is achieved so that is why I have the dilemma.
You can go straight to the camera with boom and lav. The main problem with that is who is going to monitor the level? While you are holding the camera up to your eye and the subject starts talking louder will you be able to adjust the input level at the camera? (doubtful). If you are having someone hold a boom why not get a competent audio guy that can also carry a 2 or 3 channel field mixer around and monitor the levels for you. Documetary's are usually a one take deal and if the audio is distorted or too low then the piece is pretty useless.
Just to add to everyones great advise. I did a bunch of interviews last year on the road, did not bring my 302 mixer, trying to adjust levels in the camera is a pain, think about it, what ever camera you are using you have to TOUCH the camera while shooting.
For the recent set of interviews I did I bought along the mixer, granted a little more setup but the audio was great. Was able to control the 2 mics and keep the levels constant, in post the editor was happy as could be , said he didn't even touch the audio.