What Is a Telephoto Lens?

Mary McMahon
Mary McMahon

A telephoto lens is a camera lens designed to enable people to take long focal length pictures using a lens with an actual length which is shorter than the focal length. For example, a 400mm telephoto lens is not in fact 400mm long, unlike a conventional 400mm lens. There are a number of reasons why people might want to use this type of lens, ranging from the need to have a camera which is easier to handle but still capable of long focal length images to a desire to take advantage of specific traits of these lenses.

Many telephoto lenses are extremely long.
Many telephoto lenses are extremely long.

When people hear the phrase “telephoto lens,” they often think of an extremely long camera lens. Some telephoto lenses are quite long, but this is not necessarily so, and long lenses aren't always telephoto. This term refers to a lens of a very specific construction, not a particular length.

Photographers typically take portraits with telephoto lenses to throw off -- or blur -- the background.
Photographers typically take portraits with telephoto lenses to throw off -- or blur -- the background.

In a telephoto lens, there is a lens element at the front of the camera just as there is with other cameras, but there is a second element in the back of the lens in front of the film which acts to magnify the front lens. This second element effectively increases the focal length of the camera by making it seem as though the first lens is further away than it really is. Historically, a telephoto effect was sometimes accomplished with the use of lenses positioned in front of an optical instrument, but today the structure is built right into the lens.

The primary reason to use this type of lens is to take photographs of objects at a distance. A lens with a short focal length cannot take good images of things in the distance. The longer the focal length, the more detail can be seen in the distance. With a telephoto lens, a certain amount of compression also occurs, with more objects fitting into the visual field. As focal length decreases, depth of field widens, which changes the look and feel of the image.

People often want to take images with a long focal length, as for example when someone on the shore wants to take pictures of boats. However, the lenses needed for such photographs can become very long and cumbersome. They make the camera hard to handle and they also put strain on the lens mount and can damage it. A telephoto allows photographers to have the best of both worlds in the form of long focal length and a shorter lens.

Camera lenses that have several glass elements tend to create lens flare -- often seen as scattered light circles or halos.
Camera lenses that have several glass elements tend to create lens flare -- often seen as scattered light circles or halos.
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments


One of the funniest parts about the term telephoto lens is that people often will refer the image of a really long lens or a lens that you can take a picture of the moon with. This is not always the case and a good example of this is the macro telephoto lens and the many varieties of it that are available to photographers.

A macro telephoto lens means that you can have a very up close view but are still able to stand back a bit from the object that you are photographing. In this sense, you are not photographing something very far away at all but you can still get into a very detailed view of whatever that object might be.


Unlike what the author of this article claims, the term telephoto lens does in fact refer to a focal length. It doesn't have anything to do with the actual size of the construction or the housing size. When you look up the definition of telephoto lens then you would understand this.

I recommend that anyone who is truly interested in photography, make sure that you have a selection of focal lengths available to you as that way you can shoot in any situation that you need to. Most people will never need to photograph something that will require more then a 400mm lens but if you are interested in wild life photography then you might want to invest in some super telephoto lenses.


Canon and Nikon telephoto lenses offer a great variety of choices as far as overall quality and performance. While people will always debate the two brands much like people debate what car is better, a Ford or a Chevy, the real comparison must be made on some type of standard level in which the two can be put side by side and understood.

I have been very happy with my consumer grade Canon 75-300 that is not a professional lens by any means but it does all of the tasks that I ask of it.

I have been eyeballing a very expensive but reputable lens made by Canon that has a focal length of 70mm-200mm. While the lens may not have the same reach that my other Canon lens has, it does have a maximum aperture of ƒ/2.8. This allows someone to shoot in very dark situations while still getting a sharp image. We call these fast lenses and they are worth every penny.


The type of telephoto lenses that are available on the market to photographers today vary greatly in price and quality. Many consumer grade lenses offer a wide range of focal lengths in small and affordable packages that seem very alluring when comparing prices on lenses. One thing that should be noted however, when you do research for the type of telephoto lens to purchase, be sure to examine the specifications of the aperture on the lens. There is no direct comparison or ratio of focal length to price so you must be sure that you are getting the kind of lens that best suits the needs you have for it.

While a typical consumer grade telephoto lens can cost somewhere between $200 and $400 dollars, these types of low end telephotos only offer a maximum aperture range usually between ƒ/4.5 and ƒ/5.6. This of course is just fine if you are going to be taking all of your pictures in brightly lit situations only.

If you are a parent of a football player that plays their games in the evening times then you might want to consider that your needs are much different then a soccer mom that is taking photos only in the day time. As soon as you start looking at lenses that offer an aperture in the range of ƒ/2.8, the cost of the lens can soar into the thousands of dollars.

In photography, you usually will pay for the amount of light that a lens can soak up, not really the focal length of the lens that you are using.

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