Certain types of lenses are better for certain situations, so it’s important to know their classifications and differences. The first thing worth noting is the difference between zoom lenses and prime lenses. Zoom lenses—as you can probably guess—let you zoom in and out. While they have that advantage, they’re generally more expensive, heavier, and larger. Prime lenses, on the other hand, do not allow you to zoom, but they’re often cheaper, lighter, and smaller. In many cases, prime lenses will provide sharper images than zoom lenses at lower price points. When you start paying thousands of dollars for lenses, lens performance tends to be a little more equal.
The next thing you want to understand is the difference between wide-angle, standard, medium, telephoto, and ultra telephoto lenses. These terms are all based on a lens’ focal length, which is a complex definition that’s beyond the scope of this lesson (if curiosity compels you, read about it on Wikipedia). What you need to know is that focal length is measured in millimeters (mm) and you can think of it like the amount of magnification. A low number is like being zoomed really far out, and a high number really far in. Here’s what you need to know about each type:
Wide-angle lenses are essentially any lenses with a focal length of up to 35mm. The wider the lens (and lower the focal length), the more the lens can see. Fisheye lenses are extremely wide and often have a rating of around 8-10mm. A regular wide-angle lens is generally around 14-28mm. As you can see from the photo on the left, wide angle lenses capture more stuff in the frame. They also distort space, increasing depth and making it look more spherical. This can be both a wanted and unwanted effect, depending on the circumstances. Some wide-angle lenses include technology that corrects this distortion, but those lenses are almost always significantly more expensive.
Standard lenses are generally between 35-50mm and tend to most closely represent space the way the human eye sees it. Wide-angle lenses tend to distort space and add the appearance of more depth. Telephoto lenses flatten space. Standard lenses are the middle ground and produce images that look realistic to most people. A 50mm prime lens is often the cheapest lens you can buy with a level of quality that rivals zoom lenses priced at several hundred dollars more. Standards are the most versatile lenses because they’re a good compromise between the more extreme types, but they’re often useless when you’re in a small space and need to go wide or are far away from your subject and need the magnification power of a telephoto.
Medium lenses generally fall into the range of 60-100mm and are generally not a type you’ll want as a prime unless you have a specific purpose in mind (some prefer 60mm and 85mm prime lenses for portraits, for example). This range is often encompassed by zoom lenses, and that’s generally where you’ll want it. Many standard zoom lenses start as wide as 28mm and end up at 70mm, at least. A good standard zoom will encompass this range.
Telephoto lenses are what you want for zooming in really far. Pretty much anything over 100mm is considered a telephoto lens, and anything over 400mm is considered an ultra telephoto lens. While telephoto lenses can magnify an image many times over, and are necessary when you can’t get close to your subject, they’re both heavy, are more subject to motion blur (as a result of camera movement), and do not perform as well in low light. You will find some options that are compact, come with image stabilization (to prevent motion blur), and offer wider apertures (to perform better in low light), but all of these features increase their cost significantly.