Thought Id tell you about something I did today to great effect.
I had to shoot a series of presentations for a big company in a board room environment. I was working solo, 2 cameras and radio mics etc.
The fan noise from the ceiling mounted video projector was pretty bad, and they needed it for powerpoints, so it couldnt be turnmed off, nor could the air con.
So my recordings had quite a lot of air noise on them but there was nothing I could do at the venue, EXCEPT make an additional recording to allow its removal back in pro tools.
I recorded the presentations using a radio Sennheiser g3.
After all were done I cleared the room and using the SAME mic in the SAME position at the SAMR recording level, made a 1 min recording of just the room noise.
In Pro tools i added a new track of this room noise, zoomed RIGHT IN and synced up the wave form shapes in a period of re record silence, and then mono'd it all up and phase reversed the room tone. This dry room tone recording phase removes the room tone in the good recording, cleaning up NO end.
If fact it was too clean so i added a little back in.
A good trick for people to be aware of when there is extraneous noise (that can be repeated / re created exactly)