If you only have one vocal mic choice, but need to record lead and background vocals from the same singer, take advantage of a condenser microphone’s proximity effect, to give each track a distinct identity.
Microphones can be pointed towards or away from sounds. If its pointed away from the source, the mic will not "hear" the sound as well or clearly. We'll reveiw the most common polar patterns to help you determine the microphone's "front" and "back".