Telephoto and zoom lenses are often confused for being the same thing, but there are some very important differences.
The main difference between telephoto lenses and zoom lenses is that a telephoto lens has a longer focal length while a zoom lens can change focal lengths but start and end at any focal length.
One of the reasons they can often be confused with each other is that many think of “zooming in” on something, making it appear larger in the frame.
In fact the two are not mutually exclusive. You can have a telephoto lens that is also a zoom lens and you can have a zoom lens that isn’t a telephoto.
What Is a Zoom Lens?
Zoom lenses are designed to zoom.
That’s as simple a definition of zoom lenses that I can give you. But it’s not that simple. The underlying technology is a bit complicated. The whole purpose of designing these lenses is so that you’re able to use different focal lengths using a single lens unit. In other words, the Angle of View of the lens is variable.
If I lost you there, let me explain what’s Angle of View is for you.
The angle of view is the extent of the scene in front of the lens that’s captured by the camera. When the lens’ focal length changes, so do the Angle of View and with it the extent of the scene captured by the camera.
The longer the focal length, the narrow the angle of view is and the shorter the focal length, the wider the angle of view is.
A narrow angle of view will give you a more zoomed-in image (ie. closer to objects that are far away)
Let’s take an example to illustrate…
The 24-70mm is a zoom lens.
How do I know that? Because of the two numbers on the lens body – 24 and 70mm. It suggests that the focal length of the lens is variable and it’s 24 to 70mm. Therefore this is a zoom lens.
24mm and 70mm are the shortest and longest focal lengths that lens can adjust to. When the focal length is at 24mm, the lens will see a larger slice of the scene in front, and therefore the camera will be able to capture a wide-angle shot.
At 70mm, the focal length gets longer, and therefore the lens sees a smaller slice of the scene in front and that’s what the camera captures.
Also, at 70mm, you are getting close to a short telephoto focal length, which many consider to begin at about 85mm.
Photo Terminology: Lenses that don’t have a variable focal length, in other words, their focal length is fixed, are known as Prime lenses.
What Is a Telephoto Lens?
Telephoto lenses are those which has a minimum focal length of 85mm or more.
The range from 85mm to 135mm is commonly known as a short telephoto lens. 135mm to 300mm is medium telephoto. Finally, anything longer than 300mm is known as a super-telephoto lens.
A telephoto lens can be either a zoom lens or a prime lens.
Often, the super telephoto lenses, like the one shown below, are prime lenses because the size needed to make a zoom lens at such a long focal length and wide aperture would be impractical. As it is, the 400mm f/2.8 lens below is difficult to use without a monopod to hold it up!
Can a Telephoto Lens Be a Zoom Lens Too?
We understood what zoom lenses are. These are lenses with variable focal lengths. A telephoto lens be a zoom lens as well. A telephoto lens can be a zoom lens because there are telephoto lenses do come with variable focal lengths.
Let’s take an example…
The Nikkor 200-500mm f/5.6 ED VR is a sample lens that I pick for this. This lens has a variable focal length range that starts from 200mm and goes all the way up to 500mm.
As we have just learned above, any lens with a focal length over 400mm is considered a super-telephoto lens. Therefore the 200-500mm f/5.6 ED VR is a super-telephoto lens at its longest focal length.
The Main Differences Between Telephoto and a Zoom Lens
Telephoto lenses can be of a fixed focal length.
Zoom lenses are always variable focal length lenses. Telephoto lenses use longer focal lengths and can be zoom or prime lenses. Zoom lenses can be shorter in length. Telephoto lenses cover a thin slice of the scene. They have a longer focal length.
Zoom lenses can be wide-angle lenses and cover a wider slice of the scene.
Uses of Telephoto Lenses
As you can imagine, telephoto lenses are designed to capture objects that are further away from the photographer. They have magnification elements inside the barrel which can bring distant objects closer to the camera. Very similar to what a telescope would do.
The major use of such a lens, therefore, is to shoot objects that are difficult to get very close to. Wildlife e.g. is something that is the best shot using a telephoto lens. If you’re shooting landscapes, like close-ups of mountains, etc. Telephoto lenses are the way to go.
Also, these lenses are used when getting close to a subject can be hazardous or even unfeasible, such as when you’re photographing motorsports or photographing a soccer game, etc.
Some short and medium telephoto lenses are used for portrait photography like the 135mm f/2 prime.
Uses of Zoom Lenses
Zoom lenses are ideally suitable in situations where carrying more than one lens is not feasible. Let’s say that you’re packing for a weekend trip or a family get-together. You know that you’re going to pack light and that means leaving behind everything that’s not necessary.
As photographers, we like to carry everything that we own when leaving our home, but that’s not possible. We have to choose what equipment we need and what to leave behind. Zoom lenses give us the option to pick more than one lens because they’re versatile. They have variable focal lengths and that means they function like two or more lenses in one.
Telephoto lenses and zoom lenses are not two different things. They’re just names assigned to lenses that fit a certain profile. The definition overlaps and that’s why it’s possible to have a lens to be both a telephoto lens and a zoom lens at the same time.
Interestingly, however, all zoom lenses are not telephoto lenses and conversely, all telephoto lenses are not zoomed lenses either.
Hope the above discussion was able to give you a clear understanding of what these two lens segments are all about and be able to choose the right lens depending upon your needs.