Canon Rebel T2i Quick Start Manual page 104

Directionality: Pick-up (or Polar) Patterns
This chart and image on the following slide are reproduced from p. 27 of the Shure Microphone Techniques Recording
Manual, Shure Education Publications, 2014. This publication can be downloaded free from the Shure website.
I highly recommend it!
Microphones do not only pick up sound
from what they are pointing at. They can
have a spherical (omni-directional) or
more directional (hyper-cardiod) pick-up
pattern.
Each one of these patterns cancels out
sound from behind the microphone.
Look at the angle of rejection (of sound)
on the chart and the amount of rear
rejection.