mwsilvers wrote:
Prime lenses also tend to be faster lenses, meaning wider apertures which allow in more light. Not all primes are fast, but generally short focal length primes have maximum apertures ranging from f/1.2 to f/2.8.This allows you to take photographs in low light and still maintain a moderate shutter speed and reasonable ISO levels.
Another advantage is that with f/2.8 and faster lenses, many autofocus systems work faster and more accurately.