The lens you get when you buy a DSLR — generally a standard 18-55mm zoom — is designed for some level of versatility, but it doesn’t capture particularly sharp images, and it doesn’t have any special features. When you go to find a new lens, most of your options aren’t as versatile but handle specific things very well. Let’s go over what types of lenses you can get and why you would want them.
Learn the Lens Basics
Before we get into the various types of lenses, it’s important to know a few terms and basic ideas about lenses so that you can understand what they mean when you’re shopping around. Lenses are labelled like this: 18-55mm f/3.5-5.6. That designation tells you a lot but doesn’t mean much if you don’t know a few terms. In this section we’ll learn what you need to know to understand how lenses are labelled and what those labels mean.
Zoom Lenses vs Prime Lenses
Both zoom and prime lenses are designated by their focal length. Focal length is often measured in millimetres (mm) and designates the distance at which something is in focus. This definition doesn’t mean much practically speaking, so what you want to remember about focal distance is that lower numbers indicate a wider view (zoomed out) and larger numbers indicate a closer view (zoomed in). For example, if you’re photographing a small room in a house and you used an 18mm lens, you would likely capture the majority of the room in your image, while you would get very little of the room with an 85mm lens. Primes only have one focal length, and so they’re simply labelled as 35mm, 50mm and so on. Zooms offer a range, and so they’re labelled as 18-55, indicating that you can achieve a focal length as wide as 18mm, as close as 55mm and everything in between.
You’re not stuck with a single aperture. When a lens is rated a nice, wide aperture like f/1.8 that just designates its maximum. You can change the aperture on your camera to a narrower aperture to allow less light. Why would you do this? Narrower apertures provide a greater depth of field, meaning that more of the image will be in focus. When you’re photographing a landscape, you want the entire image to be in focus and not just the part of the plane that your camera focused on. A higher, narrower aperture (f/12) provides that. A wider aperture (f/2.8) would make the landscape appear less sharp. That said, you don’t always want everything in focus. When taking a portrait, for example, wide apertures are wonderful because you can focus on a person and allow the background to blur away. As demonstrated in the example photo to the above right, the only things in focus are the aperture blades of the lens. A wider aperture made this possible.
Put it All Together
Now that you understand focal length and aperture, you can read lens titles and know what they mean. Let’s take the standard zoom lens you already have and break it down. Most likely it has a label of 18-55mm f/3.5-5.6. You know the first part, 18-55mm, means the lens can capture a view as wide as 18mm and zoom in as close as 55mm. You know the second part, f/3.5-5.6, means that the lens has a maximum aperture of f/3.5 when zoomed out to 18mm and f/5.6 when zoomed in to 55mm. But what does that mean in practical use? For that you need to understand what different types of lenses can do.
Types of Lenses
Lenses have various designations based on their focal length. Generally speaking, a lens with a very wide field of view exaggerates depth and one with a narrow field of view flattens depth. Changing focal lengths, whether that’s by using a zoom lens or changing between different primes, allows you to achieve different affects with your photos. In this section we’ll discuss the common categories of lenses and what you can do with them.
Note: Each lens category will contain a range of focal lengths. If you own a standard DSLR camera, it likely has an APS-C sensor inside. APS-C sensors magnify focal lengths by approximately 1.6 times. That means a 50mm lens essentially becomes an 80mm lens (as 50 x 1.6 = 80). This is important because this magnification can potentially make a lens in one category into a lens in another category. Bear this in mind when shopping, unless you know your camera has a full-frame (35mm equivalent) sensor and the 1.6x magnification doesn’t apply to you.
Fisheye (12mm or less)
Wide Angle (18-30mm)
Super Telephoto (300mm or more)
Special Types of Lenses
Special lenses can be a lot of fun, but since you’re just starting out, you’ll probably want to avoid them. They not only add more cost but more complexity to the process of capturing an image. When you’re purchasing lenses, start with the basics. Once you have more control over a regular lens, you’ll be able to do more with a lens that has a special feature (or two). If you want to learn more about the basics of photography, you should also check out our night school course. There’s a lot to learn, but you can pick it up quickly if you keep practising. The great thing about photography is that you can do it almost anywhere. Enjoy whatever new lens (or lenses) you choose and have fun testing their possibilities.