On-Camera Sound - What Do You Do with 2 Channels?
 

Let's say I've got a Sony Z1U, an AT4073a mic on a boom pole and a Sennheiser lavalier mic. I also have a mixer (although I don't have to use it).

Assuming I've got two actors speaking in a scene - what am I trying to capture to my on-camera stereo audio? Should I give the lavalier to one actor and boom mic the other - recording each actor on a discrete channel? Do I skip the lavalier and just record both with the boom run through a mixer? If I use a mixer, is there any point in placing other mics - like piezo mics or laveliers around the room to pick up natural ambience or will that just muddy my dialogue?

Many thanks for any pointers!

Hmm, I seem to have the same dilemma. Going to be shooting with an XL2, no mixer is available. Two actors, sitting about 3 feet apart in a diner. There will be ambient/environment noise from customers. There are several ways to go about this but I'm not sure which one is the right one.

1. Just only a boom, put it between the actors.
2. Use a boom and a lav, boom between, try to hide the lav on the table.
2. Boom between, lav only one actor and hope the other one speaks up.
4. Lav both, use the boom for ambient sound gathered later.
5. Boom pointed towards one actor, lav gets the other.

Haven't gotten a definitive answer yet from everyone I've asked.

You probably won't get a definitive, because this is a hard one to gauge. If you don't have a good interior mic to put on the boom, or if you don't have a boom op that really knows his stuff, or if you've got an omni lav in a noisy room, these all come into play.
Shotguns are rarely optimal for interiors, and can actually be worse depending on the room itself. A highly reflective room with a lot of low frequency information in it can be horrible with a shotgun.
Do a search here in the forums and read up a bit on various small diaphragms that are used for interiors, that's a good place to start.
Next, don't consider your sound as "stereo" but rather two discreet channels. (dual mono) Why not feed it with both and when necessary, switch between the two mics? You'll definitely notice a shift in the sound, but one or the other might save your sound. Think of it as two opportunities to capture audio.
FWIW, you'd likely be better off using two lavs if you don't have a good mic for a boom.

Well, this question begs the question.... How many takes and how much coverage will you have?

Is it a 1-take 2-Shot and you have to be outta there? or will you do 3 different setups with a backup wide-side setup?

See, if its just a single 1-take 2-shot setup, then you're screwed. All you can do is use the boom and split the difference, or make your boom operator study the script, and have him adjust to the conversation based on who's speaking next.

However, if you are allowed the opportunity to shoot multiple setups for better coverage, then Boom the actor individually in his/her cameo shot, run the lines and put the lav on the OS(off screen) actor for reference. Do this for both actors. Then shoot your wide 2-shot and use the boom splitting the difference between actors and place the lav on who's most important, on the table, or on who you will never see again (the one you cant get into the studio at a later date). Do the same thing for your wide-side shot. This ofcourse will require your actors to repeat the same lines atleast 4 times, but...hey, that's the business.

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