noise rejection help

[jmo1987]

hey everyone, im somewhat new to the film industry. ive worked in a recording studio, set up church sound systems, and done some filming for random events. i now work for a small production company and am starting as a boom operator. my first question involves noise rejection. our recent corporate jobs have been on a green screen using a shotgun mic so a little help on this subject would be great. maybe a link or some advice as to what rear axis or off axis noise reduction is.


thanks

 

[Alex H.]

Every mic has a response patter that includes angles at which the mic accepts the most signal and at which it rejects the most (save for omnidirectionsl, which takes sound from all directions... hence the name).

Shotguns are designed to have a narrow response pattern, so that sounds coming into the mic from directly in front are accepted above all else. Off-axis, or angle of rejection, would be to the sides and rear. Consult your mic's manufacturer-supplied specs for exacts.

in short, you can use the angle of rejection to tune out extraneous noise (to an extent) by pointing the off-axis rejection at the noise source while keeping the capsule aimed at the desired source.

 

[TyFord]

As C2V mentions, shotguns have a narrow angle of acceptance. THIS IS REALLY IMPORTANT!!
Narrow at HIGH FREQUENCIES. Not so narrow at mid and low frequencies. That's why shotgun mics are not advised for use in interiors or any in highly reflective environments. They are a lot more omnidirectional at mids and lows. That's a problem.

For those situations, you want a super or hyper cardioid like a Schoeps cmc641, an Audio Technica 4053a or Audix SCX-1 HC. The Schoeps is the best. You'll find it on movie sets. I own two and use them for lots of other jobs tham boom mic.

Regards,

Ty Ford