What is a prime lens?

Canon 50mm Prime Lens 1.8f

A particularly popular, versatile, and inexpensive prime lens: the Canon 50mm 1.8f

A prime lens is a camera lens with a fixed focal length.  This is as opposed to a zoom lens, which can be adjusted to a range of focal lengths.

While each prime lens restricts you to one focal length, they have a number of advantages over zoom lenses.  Because a prime lens is simpler to construct, a cheap prime lens can often produce much better quality photos than a more expensive zoom lens.

Prime lenses are also typically lighter in weight, for more ergonomic and more mobile photography.  They usually feature much larger apertures than equivalently priced zoom lenses, for better photography in low-light settings and at higher shutter speeds.  This also allows for a shallower depth-of-field, using blur to effectively and strikingly isolate your subject from foreground and background.

While a prime lens doesn’t provide all the flexibility of a zoom, you might find that you enjoy having to “zoom with your feet,” as it compels you to explore new perspectives and angles in composing your photographs  Because of their image quality, simplicity, and relative low price, many photographers like to have at least one prime lens in their DSLR kit.

Focal lengths range from ultra-wide to wide angle to telephoto, with some lenses optimized for macro photography.  A 50mm prime used to be the standard lens that came with all film SLR cameras, and many people find this to be an ideal lens for a wide range of subjects.  A longer lens, such as an 80mm, 105mm, or 135mm is great for portraits, and a wider lens like a 24mm, 28mm, or 35mm can be great for capturing large swaths of a landscape, urban, or indoor environment.