What Is a Telephoto lens?

Telephoto lenses are very popular in the photographic world. They are the really long lenses that cover many photography disciplines. You will often see sports, wildlife, landscape and astrophotographers carrying around a telephoto lens.
A telephoto will help you understand your relationship with your scene. And let you photograph dangerous situations without having to get too close.
Before running out and purchasing one of these beasts, think long and hard about how much you are going to use it.

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Telephoto, just like every other type of lens, comes in two different formats: prime or zoom. A prime version has a fixed focal length, meaning it can’t change. Here, to get closer or further away from a subject, you need to move your feet. The Canon EF 300mm f/4L IS USM is a perfect example.
The zoom version has a variable focal length and will allow you to get closer and further away by moving the lens’ zoom ring. The Canon EF 70-200mm f/2.8L is a great example of the zoom lens.

Apart from letting you photograph subjects from a distance, they affect the background of your scene. They do this much differently than other lenses, such as a wide-angle or standard lens.
A telephoto lens will have a focal range of anything above 70 mm, but they come in different sizes. A medium telephoto lens covers between a 30° and 10° field of view (67mm to 206mm at full frame). A super telephoto lens covers between 8° through less than 1° field of view (over 300mm at full frame).

Pros and Cons

Just like any lens type, there are benefits and drawbacks. Physically, the best thing about a telephoto lens is that they often come with a stabiliser. Blur due to camera shake is a big problem in photography, and more so when it comes to telephoto lenses.
The Image Stabiliser is an in-lens element that cuts down camera shake. Telephoto lenses need this when a tripod isn’t available.
These lenses are heavy. They look heavy due to their size. They can even be heavier, depending on the aperture range and whether it is a zoom lens or prime.
To make a fast aperture zoom lens requires many electronic parts inside, all adding to the weight. The Canon EF 100-400mm f/4.5-5.6L is 1.5 kilograms. That is holding one and a half bags of sugar, not adding the weight of your camera.
Apart from adding weight to your journey, they take up space in your bag. Unless you have a zoom lens such as the Canon EF 70-200mm f/2.8L IS II, the lens isn’t really versatile.
A fixed focal length prime telephoto lens is even less versatile. This means that these lenses become very expensive if you don’t use them all that much.

Background

One purpose of a telephoto lens is blurring out the background. This can be done with other lenses of course, but the telephoto lens creates a very different out-of-focus effect.
The effect of an aperture of f/2.8 on a background is much greater with a telephoto lens than with a standard lens. This is down to the background becoming ‘stretched’. As the field of view is smaller with a telephoto lens, there is physically less background to fill in the frame.
So if you wanted to dramatically put a background out-of-focus, use a telephoto lens.
The other area that we need to talk about is lens compression. Lens compression occurs when you take a picture with a telephoto lens, but it isn’t down to the lens or its focal length.
It is because we stand farther away from our subjects when we use a long lens. The camera-to-subject distance gives the viewer the impression that distant objects are larger than they actually are.
This makes it look as if the background has been pulled closer to the subject. You may know this technique as image flattening.

Perspective

Telephotos are great at capturing portraits, as long as you have adequate space to move back to get the subject in the frame. This isn’t best for studio photography, but definitely usable in the outdoors. Objects appear closer to the other objects in the frame when using a telephoto lens.
A longer focal length forces the foreground to appear to get smaller relative to the background. This allows those facial features to look more proportional. Also, you get that beautiful bokeh in the background, which is a great addition to portraiture, making the subject more interesting.

Recommendations

DSLR – Canon

The Canon EF 100-400mm f/4.5-5.6L IS II USM is a relatively portable package with fast, ultrasonic-type autofocus and optical image stabilisation. It’s impressively sharp at all focal lengths and comes in white to better deal with the outdoor temperatures.
If you want the lens to reach 160mm – 640mm range, then drop it on an APS-C camera body.

DSLR – Nikon

The Nikon AF-S Nikkor 200-500mm f/5.6E ED VR AF-S is a relatively affordable telephoto lens while offering a very useful long telephoto range.
The f/5.6 makes is portable and useful, and it isn’t too heavy either, weighing in at 1.4 kilos. Handheld shooting is possible. The AF-S mode makes the camera fast at focusing and accurate.

Mirrorless – Panasonic

The Panasonic Lumix G Vario 100-300mm f/4-5.6 II OIS is a hugely popular lens within the mirrorless community. As it works with the four-thirds system, the equivalent focal length goes all the way up to 600mm.
It is a very compact package, with image stabilisation and fast, silent focusing. This version has weather sealing, so no problem using it out in the elements.

Mirrorless – Fuji

The Fujifilm XF 100-400mm f/4.5-5.6R LM OIS WR is the only lens Fujifilm X-system users have for long telephoto lenses work. A lightweight build and very effective image stabiliser make this the perfect handheld lens.
It even has a weather-sealed construction. It is equivalent to 600mm, but you can go longer with the Fujifilm’s 1.4x teleconverter for an extra cost.

For All Those Sony Lovers

The Sony FE 100-400mm f/4.5-5.6 GM OSS is Sony’s longest lens for its mirrorless cameras. This lens has a direct drive SSM for fast and quiet precise focus. Perfect for not disturbing the wildlife.
The optical SteadyShot image stabilization significantly reduces blur, which is really needed when photographing at its most extreme focal length. The aperture isn’t super wide, but it is what you’d expect for a lens of this magnitude.