Telephoto Lenses
What is a telephoto lens?
A telephoto lens is basically a camera lens that magnifies distant objects. In that sense it’s a little bit like a telescope—just not quite as powerful! In terms of focal length, it is generally considered that a 50mm lens provides a field of view that is roughly equivalent to the human eye, so a telephoto lens can be classified as anything above a 50mm. In reality, most photographers will look for a focal length range roughly equivalent to 70-200mm, although sports and wildlife photographers might want a much higher maximum focal length like 600mm.
What are the advantages of a telephoto lens?
The number one advantage of a telephoto lens is that it allows you to get close-up photos of subjects that you cannot get physically closer to. This is why they are go-to lenses for wildlife photographers and sports photographers. When you are photographing wildlife, it’s generally better to be inconspicuous and move as little as possible because wild animals have learned to be shy and elusive around humans. A long telephoto lens will allow you to overcome the barrier of distance and photograph, for example, rare birds. Sports photographers are similarly constrained as they often have to pick a single vantage point from which to cover an event and a telephoto lens allows them to get close ups of the action that would otherwise be impossible to get.
Telephoto lenses for portraits
The lens of choice for many portrait photographers is an 85mm lens, but many will use a 70-20mm lens. There are a couple of reasons why portrait photographers love telephoto lenses. First of all, they are the most flattering to human subjects. Wide angle lenses suffer from a sort of bloating effect (known as barrel distortion), which at its most extreme is referred to as the ‘fish-eye’ effect. Telephoto lenses don’t suffer from barrel distortion and so they are great for photographing people. The second reason portrait photographers love telephoto lenses is because they are capable of creating beautifully blurred backgrounds which makes portrait subjects really pop. With shorter focal length lenses you need a wide maximum aperture to create this effect (often referred to as the Bokeh effect), but with telephoto lenses its just a matter of increasing the focal length and the distance to your subject.
The difference between a telephoto lens and other lenses
Telephoto lenses are often much larger and heavier than wider angle lenses. If you take a look at some of the larger telephoto lenses from Canon, Nikon or Sony, you’ll notice that they have a mount that allows you to attach them directly to your tripod. This is helpful because it takes account of the fact that the center of gravity of your set up is now much further forward, which could potentially leave your system poorly balanced.
Faster shutter speeds are required
Another key difference with telephoto lenses is that they require faster shutter speeds in order to mitigate the effect of camera shake which is exacerbated by the length of the lens. The rule of thumb is that the shutter speed should be at least twice the focal length, so for example at 200mm the shutter speed should be at least 1/400s. Many of the more expensive telephoto lenses will incorporate stabilization to combat this problem, and nowadays we’re seeing more and more cameras with in-body stabilization.