Please correct me if I'm wrong and confused, but I'd like to clear this up. A lot of people are calling a 50 mm f1/8 a prime lens, and zoom lenses non primes when the opposite could be true. It is my understanding that a prime lense is a manufacturers premium lens, be it a zoom or single focal length. Like Nikons 28-70mm f2.8D would be a prime lens as would the 200 mm f2 because of the build quality. Where as, a 50mm f1.8 is not considered a prime since it is usually cheaply made.