A friend is shooting a commercial on spec for a local quick-service restaurant, and has asked me to help with getting good audio for him. It will be a static shot indoors. I realize a shotgun mic and boom pole are preferred but there's no budget to rent. I have Neumann KM-184's and AKG 480/ck63's. I assume the AKG would be preferable? Any other tips from anyone who's done this before?
The "secret" to dialog recording is that signal-to-noise ratio is really about locating the mic properly. Specifically, it's about how close you can get to the speaker's mouth.
Why is this important to you? Reflections. Besides extraneous noise from coolers, HVAC, etc., when your talent speaks, the room is going to reflect that sound. Being close allows you to turn down the gain, which in turn makes the room noises and reflections softer compared to the dialog you want to hear. It's really just that simple. And this is exactly why the very worst place you can put a mic is on the camera. Very worst. Because the mic is way too far away, and it's not pointed at the right spot anyway. Amateur hour.
The way booming works is you put the mic above the talent's head just out of frame for the video, and out in front of the talent so that you can point the mic at talent's mouth at about a 45 degree angle. If you do it right you can usually get the distance from mic to talent's mouth down to that 45-60 cm range. Unfortunately for you, that's not close enough for a cardioid, and is one of the main reasons hypercardioid mics are typically used for indoor dialog work. You can do this with a cardioid, but it won't have the "reach" of a hyper, and thus your capture will include more room reflections that you might want (your dialog will start to sound "boxy").
The reason you don't want to use a shotgun mic indoors is because of it's rear lobe. It picks up reflections in the opposite direction the mic is pointed, and if you're booming above the talent, the rear lobe usually ends up perilously close to the ceiling and picks up all sorts of nastyness. Also the diffraction tube will do some comb filtering of reflections from the sides (and of course the ceiling) -- if the reflections are close enough in time to the direct sound from talent, it can be dreadful.
Where does that leave you? Two ways to go maybe. One is to give in and let the mic be in the shot. Use a reporters stick mic like the very popular
Electro-Voice RE50N/D-B (just about every local news crew in the US uses these, so look at how they use them and train you talent appropriately). Alternatively, you can use a lavalier mic, either concealed or not. If you go down the lavalier path, use only omni mics. Do not use directional mics. You won't believe it, but there are extremely good reasons that no one uses anything but omnis, and I've run out of time to go into any more depth.
Sorry, I know it's not what you wanted to hear. But the laws of physics are the laws of physics.