There are a number of obvious technical advantages of a prime lens over their zoom companions (sharpness, wider aperture, less distortion in most cases), but covered in this post will be the mental reason why to use primes over zooms. This is not to say that primes are the prefered lenses for all cases, nor that have not a place in the wise photographer’s gear bag. Each tool has its uses, but the prime lens is a tool of amazing power, largely for intangible reasons. The prime lens is the ultimate lens for photographic creativity, not only because the broad apertures permit a beautiful shallow depth of field, but principally because they change the photographer.
First, the prime lens trains the eye. In October 2010, when I was in Colorado, my 70-300 IS fell to its death on Mount Princeton. My remaining lenses were my Sigma 10-20, Canon 50 1.4, and 300 f4 (I also had a 17-85, but wasn’t using it; if I remember right, my friend Alo had it…). I also had a 1.4x TC. Between those three lenses, few were the shots I missed. I kept the 50 1.4 on the camera most of the time, where it worked its magic. I began to see scenes through the eyes of the 50 1.4, 300 f4, or 10-20 (which is nearly a prime…). This Providential exercise taught me previsualization. Being able to see a scene before it jumps into the camera completely changes the shooting. Lame scenes are avaoided. Unseen views are made visible, as subtle details emerge in a previously overlooked view. If you wish to be a better photographer, take your 50mm prime on a walk (if you lack one, get it today! They are cheap, probably the cheapest lens you will ever buy, and they have great image quality!). Go somewhere, anywhere really, and learn to see through its eyes, if you will, and let it teach yours. You will begin to see potential pictures around you you could capture, instead of the vague undefined scene of before; which introduces our second reason, simplification.
Second, the prime lens simplifies. Instead of hunting around on a zoom lens to see how things will look, you will have but one focal length with which to be concerned at a time (you can of course have other primes in your bag, eagerly awaiting to serve their purpose!). And this will clear your mind and aid your vision, producing images with a little more thought and a little less carelessness. You will need to take a few steps back or forth to use a prime, as your feet will be your only zoom. But this will bring an added blessing: changing perspective.
Third, a prime lens illuminates the user to perspective. A zoom lens will permit the user to remain stationary as he attempts to frame his image without a bit of changed perspective. But every bit of movement of the camera causes a changed perspective. As you momove about with a prime, you will be much more aware of the relationships of the elements in your frame than you would be otherwise.
A prime lens is the ultimate photographic tool for creative photography. Try one today! This experiment is your homework: put a prime lens (of any focal length, but your life will be easier if you use one between 24 and 100…) on, and enter your front yard (or back yard, or city street, or wherever so else you may go), and take a walk around and practice seeing. Shoot carefully and thoughtfully, and practice taking creative pictures, with perspectives you don’t often use. Practice what happens when you zoom with a prime, and see what the difference a few feet of perspective can make. Try using your shallowest aperture, and see what comes out. Stop down only when absolutely needed. Let me know how it goes!