Microphones Shotgun Mic? length vs pickup distance?

[NickVon]

Is there a rough correlation between the length of a shotgun mic and it's abilty to pick up something a greater distance away while retaining rear and side rejection.

I'm looking to grab a couple, to pick up the rear of the stage a little more, and what doesn't reach our PCC160's. For, say 25 feet, is 7" enough vs 16" or is 16 inches more appropriate for 60 feet? All that i have been able to discover is that yes the longer the better pickup at range. But how long of a shotgun is overkill for 20-30feet?

For reference sake i'm looking at Rode NTG-1, and NTG 2 and the Audio Technica AT875R and AT8035.

500 dollars is the budget for the mic's alone.

Any thoughts and feedback is appreciated. google and forum searches only yielded that the generalities with pickup, but was looking for a more concrete number of feet.

 

[bishopthomas]

Yes, the longer the mic the more directional it is, and at increasingly lower frequencies. However, there is no exact calculation for length of mic to pickup distance ratio. In general, though, you get what you pay for, so don't skimp out. $500 is probably the very lowest I would want to pay for a half way decent shotgun.

 

[museav]

However, there is no exact calculation for length of mic to pickup distance ratio.

Agreed, all you can do is compare the pattern and sensitivity. Think about how ambient or background noise levels might affect how far away a mic can 'pick up' a source. Or how the acoustical environment may affect that. And what defines being able to 'pick up' a source, is it the desired signal being some certain level above the ambient level or achieving some specific level of intelligibility for spoken word or what?

Another thing to consider is the back lobe. Using the Rode NTG-1 and NTG-2 as an example, the rejection 180 degrees off axis is only about 7dB at 500Hz so if there are any noise sources behind the mic then they might limit ability to pick up a source on axis.

 

[FMEng]

See my post in the following thread

http://www.controlbooth.com/forums/sound-music-intercom/22221-inexpensive-shotgun-mics.html

 

[NickVon]

See my post in the following thread

http://www.controlbooth.com/forums/sound-music-intercom/22221-inexpensive-shotgun-mics.html

Just getting back to this:

thank you, the info was helpful and the Link to the other thread was very informative.