Through following the forum and other resources I've been hearing a lot about prime lenses. Many seem to be fans of the 50mm F1.8 primes. So here's my question (don't laugh, I'm new): I've heard that a low F stop such as 1.8 will give you a very shallow depth of field. If that's the case, doesn't that really limit your use of those prime lenses fixed at 1.8? Or am I totally missing something here?