I really love fast prime lenses for a few good reason. Let me explain what I mean by that a little bit. Fast refers to the largest aperture setting (usually between f/2.8 and f/1.2). Prime means a fixed focal length (no zooming in and out). Now that's out of the way lets talk about why you need one as a photographer. Photography is always about the light, if you don't know that then you have some more research to do. When out taking photos during the daytime (unless in the shadows) this is usually not a problem. The main reason for having a fast prime is low to ultra low light shooting, which I am a big fan of. Most of today's zoom lenses including the outrageously priced "pro" lenses only offer f/2.8 aperture at all focal lengths. This is not too bad considering the improved noise performance of even entry level dslr cameras. The problem with simply jacking up the ISO (sensitivity to light) is the photo now has alot of noise/grain which is simply not desirable. I personally own the fantastic Nikon Nikkor 50mm f/1.4 lens. Even though I shoot with a Canon body and use this lens manual focus only, it's always ready to gobble up any available light. Most beginners start out with no flash unit, which is great for learning the basics, so this type of lens is a must have in your bag. A key feature of having a large aperture lens is you can achieve a very shallow depth of field for creative purposes. Since I've been using this lens for some time now I've taken alot of photos with it. All the photos included were taken with the same 50mm lens without flash.