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What Is a Telephoto Lens?

Have you ever wondered how photographers get such detailed up-close shots of wildlife or athletes on the field? Maybe they sneak in carefully when subjects aren’t noticing, risking getting attacked or trampled? Well, of course not. They use a unique specialty tool known as the telephoto lens.

Telephoto-Lens-Illustration-01

Telephoto lenses are a niche but widely popular lens choice amongst many photographers. And they’re perfect for capturing crisp and dynamic images of faraway objects. Yet, while photographing distant subjects is one of their main uses, that’s not the end of the story. There are several other enormous advantages to using such a long lens that proves pretty useful in a wide variety of situations.

But still, what exactly is a telephoto lens? And how’s it different from a standard or wide-angle lens? Also, how can you use one to affect or improve your photography?

In this post, we’ll explore what separates these lenses from others. We’ll also cover their main advantages and disadvantages, so, by the end, you’ll understand whether they’re a worthy addition to your toolbelt.

In this guide, you’ll learn:

  • What is a telephoto lens, and why use one
  • Types of telephoto lenses
  • How telephoto lenses affect your images
  • The advantages and disadvantages of telephoto lenses

What Is a Telephoto Lens?

Technically speaking, a telephoto lens has a longer focal length than its physical length or the diagonal size of the image it takes. It’s also longer than normal lenses or those that approximate the human eye, which ranges between 35-58mm. So, any lens greater than 60mm can be considered telephoto.

Telephoto-Lens-angle of view

Yet these lenses also add a telephoto lens group, which stretches its light path. And that, in turn, reduces their Angle of View, so it now ranges between 30º to 4º, rather than 50º-63º.

Note: some photographers also refer to these as “Tele Lenses,” “Long-Focus Lenses,” or merely “Long Lenses.” But, we prefer Telephoto lenses.

However, most photographers agree that focal lengths above 70mm on full-frame are the start of telephoto, which we call “Medium Telephoto.” From there, most would argue standard telephoto lenses start around 135mm and continue to 300mm. Now, the specific areas where each category separates vary, so we will cover that in the following section.

Either way, the longer focal length of these lenses produces several effects on our images. We will cover these more in-depth later in this post, but below are the highlights.

  • They magnify distant objects, enlarging them and making them easier to photograph. And longer the focal length you use, the more magnification occurs and the larger the subject appears.
  • They add working distance to the subject. This occurs because these lenses have a smaller Angle of View, forcing you to stand further away. That added distance also foreshortens and compresses the perspective, making subjects appear more proportional in size. And that also helps you capture images with a natural sense of scale.
  • They reduce the relative depth of field in your images, letting you capture photos with a creamy background blur and excellent subject separation.

Overall, though, telephoto lenses let photographers capture a distant subject with better accuracy and isolate them against backgrounds. And that’s why they’re particularly useful for sports, wildlife, events, and photojournalism. Of course, there are other uses, but that is the main intended purpose of this lens.

Types of Telephoto Lenses

Today’s telephoto lenses are further divided into three categories. Below is a chart with the most standard telephoto lenses, their Angle of View, and their typical use case.

telephoto-lens-chart

Note: where these categories separate is highly debatable. And the names of telephoto lenses, such as short, medium, or long, also vary. Most forums, journalists, and even camera manufacturers lack a set agreement. So use the above categories as a general reference, not a hard rule. And the naming we use is just our preference on the matter.

That said, a short or medium telephoto lens is ultimately best for most photographers. This range covers many common uses of telephoto lenses, including portraiture, sports, and photojournalism. And it’s unlikely you’ll need a super-telephoto lens unless you’re doing specialized mediums, like long-range sports and wildlife, where the maximum range becomes a true necessity.

Telephoto Lenses and Sensor Size

We base the focal length measurement on the 35mm format. With that, a 200mm lens on full-frame acts like a 200mm lens. But if you use that same lens on a smaller sensor size, say as APS-C or Micro-Four-Thirds, you alter the focal length by the camera’s crop factor. Our Full-Frame vs. Cropped Sensor post discusses crop factors in detail if you want more information about how it works.

Telephoto-Lens-Sensor-Equivalent

But, simply put, you will convert that 200mm lens into either a 350mm or 400mm equivalent lens by using these cameras. It also reduces the lens’ Angle of View, increases its magnification, and brings the subject closer. And these advantages are the key reasons why photographers prefer cropped sensor cameras for heavy telephoto mediums.

How a Telephoto Lens Affects Your Images

A telephoto lens affects your image in several ways. Below are each of the main aspects it changes.

Angle of View:

Since telephoto lenses have a longer focal length than normal, they have a smaller Angle of View than other lenses. That, in turn, means they capture less of the scene ahead. And this also explains why photographers have to be far away to frame a subject properly. Feel free to review our Angle of View post for more detailed information on how this phenomenon works.

Depth of Field:

Telephoto lenses also change the apparent Depth of Field in our photos, which decreases proportionally to the subject’s distance. So, unlike a wide-angle lens, which makes more of the scene appear in focus, telephoto lenses have the opposite effect due to their high image magnification. And you’ll want to physically move further away to maintain a similar Depth of Field. Otherwise, expect the Depth of Field to be more shallow when compared to other lenses at that same distance.

Perspective and Subject Size:

Since telephoto lenses have a high image magnification, they magnify distant subjects to make them appear larger. So, to compensate for this, most photographers end up moving further away to compose. But, that added distance changes the apparent perspective in our images as well.

And it compresses the perspective, reducing the relative distances between elements, making the foreground and background appear closer together or stacked on top of one another. That also makes the subject appear larger than it would be in reality.

The below diagram shows how that apparent perspective change looks if you remain stationary but swap to longer focal lengths. And it’s the lens image magnification that causes this change.

lens-size-distance-diagram

How Telephoto Lenses Affect the Background

As mentioned above, telephoto lenses compress the relative distances of background elements since you’re standing further away. And that, in turn, reduces the sense of depth in the photo. In contrast, wide-angle lenses produce the opposite effect and exaggerate the sense of depth. Unfortunately, this change has an enormous impact on how viewers perceive your background.

So, as a rule of thumb, use a telephoto lens if you want the background elements in the photo to appear closer to the subject, and you don’t want to exaggerate their distance. Or, choose a telephoto lens to fill the background with less empty space.

However, this sense of spaciousness is essential for some mediums, like architecture or landscape photography. So, in those cases, a wide-angle lens would be better if you want to highlight a grand vista and make it appear larger by exaggerating the distance.

Telephoto-Background-Comparison

Telephoto lenses also make the background appear more blurred. And the bokeh effect with a 200mm lens at F/2.8 is far more pronounced than a 35mm lens at F2.8. However, this phenomenon isn’t caused by the lens itself, as some think.

Instead, this happens because these lenses have higher image magnification ratios, bringing background objects closer when we compensate for the distance. And that gives them the appearance of having more blur. The actual Depth of Field is the same, but the bokeh looks more out of focus since it’s larger.

So if you want to accentuate a blurry background, a telephoto lens is perfect, even more so if you can compose tightly on the subject since that will only make the effect more pronounced.

How Telephoto Lenses Affect the Subject

It’s also important to point out that telephoto lenses affect the subject of your photo, not just the background. And the added lens compression does alter their proportions in a subtle but noticeable way.

So unlike a wide-angle lens, which causes the subject’s eyes, nose, and mouth to appear further apart, a telephoto lens produces the opposite effect. And their pincushion distortion makes facial features appear closer together, slimming the subject. This effect is why many portrait photographers opt for these lenses, as most would agree it’s flattering.

What Is the Difference Between a Telephoto and Wide Angle Lens?

The difference is their focal length. A telephoto lens has a longer than average focal length, usually over 70mm, while a wide-angle lens has a shorter focal length, usually below 28mm. And this difference in focal length ultimately changes their Angle of View.

With a narrow Angle of View, telephoto lenses capture a smaller area of the scene ahead. And that makes them ideal for photographing far-away subjects in great detail. While, wide-angle lenses have a large Angle Of View, capturing more of the scene ahead. And that makes them a go-to for photographing large scenes, like landscapes or cityscapes.

These lenses also have different image magnification ratios. And that changes the relative distance and proportions of items within our photo. I covered this difference already, so you can read more about those effects in the two preceding sections.

What Is the Difference Between a Telephoto Lens and a Zoom Lens?

Many beginners confuse the terms “telephoto” and “zoom.” And it’s likely because many point and shoot cameras have optical and digital zoom functions. But, these terms aren’t identical, so I want to explain the difference.

The term “telephoto” refers to a focal length (in mm) that’s longer than the lens itself. But, most photographers don’t usually talk about it this way. Instead, most end up referring to telephoto as a means to say “zoomed in.” Or, put another way, the lens merely has a long focal length.

While the term “zoom” really means a lens with an adjustable focal length. Or, put another way, you can change how much of the scene it captures without having to move physically. Now, depending on its range, that lens may or may not be a telephoto lens. For example, a 16-35mm zoom lens is a wide-angle lens, not a telephoto one. Yet, a 24-70mm lens starts wide-angle, then moves towards telephoto.

A few more examples: a 300mm lens is also telephoto, but it isn’t a zoom lens since its focal length is fixed. However, a 100-300mm lens would be both a telephoto and a zoom lens. At the same time, the 18-55mm lens is solely a zoom lens and is too short to be considered a telephoto lens.

So think about it this way: telephoto lenses have long focal lengths, usually above 70mm. And zoom lenses have a variable range of focal lengths. With that, not all zoom lenses are telephoto, and not all telephoto lenses are zooms. Any lens can be one, the other, neither, or both.

Advantages of Telephoto Lenses

Let’s cover the most notable advantages telephoto lenses provide to us photographers.

Focusing on the Details

Since these lenses have a narrow Angle of View, they’re ideal for capturing a small area of a scene and minor details. And they help you focus the viewer’s attention to only the most essential elements within a scene, rather than have it get lost in a larger view.

Subjects Appear Closer to the Camera

The narrow Angle of View and high image magnification of these lenses also makes your subject appear closer to the camera. And this is a key reason many photographers opt for these lenses since you can take detailed photos of faraway subjects and get closer to the action. It’s also particularly helpful when you can’t or don’t want to get close to a subject, say dangerous wildlife. Plus this extra distance can also put shy subjects at ease, so they don’t run away or change behavior.

Subject Separation

Since telephoto lenses naturally have a smaller Depth of Field, unless you compensate for that by moving, they’re ideal for isolating a subject from a distracting background. And, unlike a wide-angle lens, they make it easy to have subjects stand out without unwanted background detail.

Merely use a long focal length, say 200mm, and a large aperture like F/2.8. Now the subject is perfectly focused, and the background is a creamy blur. Then moving in closer only emphasizes the effect.

Lens Compression

The compression on these lenses makes elements in the foreground, midground, and background seem stacked together. But, the benefit is that it makes photos look more proportionate. And they’re scaled to closer match how our eyes see object to background relationships.

Flattering Portraits

These lenses also create flattering portraits since they require you to move further away. And that added distance plus their lens compression makes the subject’s facial features appear smaller relative to the background, an effect called foreshortening. These lenses also have pincushion distortion, which shortens the distance of the frame’s central elements. The result is that all these factors slim the subject, making them more proportional. And this is a key advantage over shooting close up with a wide-angle lens.

Disadvantages of Telephoto Lenses

With the advantages covered, let’s now talk about the downsides of these lenses. Unfortunately, some of these disadvantages are deal-breakers to some photographers.

Camera Shake

Camera shake is always a top concern in photography. But sadly, with their large image magnification ratios, telephoto lenses emphasize the appearance of camera shake. And the settings that normally work with a wide-angle lens usually create motion blur with a telephoto lens, reducing sharpness. Not to mention, these lenses are also quite heavy, only adding to the challenge. As such, it’s best to use a tripod or enable image stabilization if you can’t use the reciprocal rule shooting handheld.

Low Light

Due to their inherent larger size, it’s rare to see these lenses offer an aperture below F/2.8. Sadly, this, combined with their susceptibility to camera shake, makes them somewhat limited in low light. So, unless you’re willing to increase your ISO, it’s best to use a tripod if you plan on using this kind of lens at night, as you’ll undoubtedly need a shutter speed below 1/200th second.

Working Distance

The narrow Angle of View and high image magnification means you’ll have to be quite far from the subject to frame them properly. If you’re shooting outdoors, that’s likely not a problem. But, if you’re indoors in a packed room, you may struggle to get enough working distance to frame the subject correctly. And this is one of the key disadvantages of these lenses for home studio photographers.

Depth of Field

The narrow Angle of View and high magnification ratio also shrink the apparent Depth of Field. And while that makes it easier to get a creamy background blur, a popular effect for portraits, it’s hard to get everything in focus when you want it. Even narrow apertures like F/13 or F/16 can still be too shallow. And you can still struggle with these values, especially when shooting close to a subject. So for large Depth of Field mediums like landscape or cityscape photography, a wide-angle lens is ultimately best, as even moderate apertures can render a scene in excellent detail. Otherwise, consider using the focus stacking technique.

Size & Weight

It’s also important to point out that these lenses are quite heavy, and they’re usually uncomfortable to hold over long periods. Even a well-reinforced camera strap will likely still cause strain with time. Their longer length also makes them slightly unwieldy and harder to maneuver quickly.

Conclusion

But, in conclusion, telephoto lenses are an excellent option when you can’t get physically close to your subject. And they’re also great if you specifically want a shallow Depth of Field or the lens compression effects they offer. That said, they’re not perfect and a must-have for every photographer. So, at least now you have a better understanding of how they work, their strengths, and whether they’re a good suit for your workflow.