for year I used a senn 816 shotgun for dialog....this allowed me to keep the mic out of camera view and get high levels of audio with the mic even 10-15 ft away from the actor.
dialog was always "crisp" ...lacking bass. I longed for the rich bass tracks from the James bond films.
working with the shotgun...you can't be lazy....the front element has to point at the actor at all times....he moves...you move....the end of the mic points to his chin.
He walks 10ft across the room...you move the 10ft with him...otherwise he move off axis of the mic and your dialog level drops down 15db.
when recording (with a Nagra) ...no filtering, no limiters....you can use a low cut filter (40hz) to eliminate small room echo...but better to use some sound blankets.
Now as I found out.....getting the "bass" in the voice.....with an 816.......the front end element of the mic points just below the actors chin with the mic only about 3ft from
the actors chest. not possible all the time.
now the reason for not filtering or limiting/compressing when recording.....you want a consistent sounding dialog track.......
in post mixing.....you will roll off lows or highs of the entire dialog track to keep all voices sounding the same throughout the entire film.
Then before mixing the dialog with the effects and music....dialog gets compressed either 3:1 or 5:1...for consistent volume....and to give it the ability to be heard and understood after the mix.
in the old days.....a mono mix for an optical sound track on film meant sticking all music effects and dialog into about -30db to 0db range.
Try playing with a mono mix of you own material to see if you can make it sound like the old tracks.
In stereo today.....the LCRS mix is with dialog only in the center channel, music -- full range 20 to 20KHZ on LRS channels , and effects about the same as music.
Un-mixed we talk about making "stems"....that is music rolls and effects rolls separately....a hold-over from making separate reels of recorded magnetic film for the pre-mix.
Now with only one channel (the Center ) handling sync dialog and all the others blaring ...you now know why you can't heard the actors in most of all the modern movie mixes today.
when recording dialog(besides mic placement)....at the head of each and every tape.....30seconds of 0db tone....for the guy to transfer all the dialog at the same level.
recording room tone? mic in the same position and volume control at same setting as used for the dialog recording....so the background noise level is same and the room tone can then be used for fill if needed.