What is a Telephoto Lens?
A telephoto lens has a focal length, or reach, which allows you to photograph a distant subject, magnify it and make it fill more of your frame. Generally, a telephoto lens with a focal length of around 70mm to 200mm is considered a ‘medium telephoto’ and anything over around 300mm is considered a ‘super telephoto’.
A telephoto can be a prime lens or a zoom lens. See below for more about prime and zoom telephoto lenses.
A telephoto lens is often used when we need to close the distance between ourselves and the subject. This makes them popular with wildlife photographers who are working with shy or timid subjects, small species of birds or mammals, dangerous subjects and also where it is important to maintain an ethical distance to reduce disturbance.
What is the Difference Between a Prime Lens and a Zoom Lens?
A prime lens has a fixed focal length and a zoom lens will cover a range of focal lengths.
Prime lenses are often associated with being higher quality as they have fewer lens elements. They are also optimised for a specific focal length. Prime lenses often have larger apertures than zoom lenses. They are constructed with fewer moving parts and often more robust.
Zoom lenses are popular due to their convenience and versatility. They have more lens elements and moving parts, so they are often associated with being lower quality and less robust. But there are exceptions to these comparisons and some modern zoom lenses are exceptionally good quality too, in image and build quality.
Do I Prefer a Prime or Telephoto Zoom Lens?
I’ve used both extensively. Generally, the primes I have used have had a faster maximum aperture so I’ve opted for these when light has been low or where I have wanted a more shallow depth of field. That said, when I’m photographing wildlife in places like Kenya or South Africa, I wouldn’t be without a good quality zoom lens. We photograph so many birds and mammals of such varying sizes at different distances so the versatility of a zoom lens is incredibly convenient.
Which Telephoto Lenses do I use?
In years gone by, my main ‘workhorse’ was the Nikkor 200-400mm f/4 lens. I also used to use a Nikkor 70-200mm f/2.8. These are both zoom lenses as they cover a range of focal lengths. I have also used the 300mm f/4 PF prime lens in Africa.
I now use Fujifilm cameras so my main lens is now the Fujinon 100-400mm f/4.5-f/5.6. I also use the Fujinon 50-140mm f/2.8. These too are both zoom lenses. I’ve also used the incredible Fujinon 200mm f/2 prime lens for the X mount, and the GFX250mm f/4 medium format lens on the GFX50s camera.
Why is There Often Such a Difference in the Size of Similar Telephoto Lenses?
It’s usually because of the maximum or widest aperture. A 300mm prime lens with a f/2.8 aperture needs to be much larger than a 300mm lens with a more narrow f/5.6 aperture.
And a Price Difference?
As a telephoto lens with a wider aperture needs to be much larger, so do the very expensive lens elements. Such lenses are usually associated with use by professional photographers where they need to be robust to cope with working in more harsh environments and are expected to be more resilient to bangs and knocks. This means more robust lens casings with additional demand for light materials which are also expensive.
What Difference Does Sensor Size Make?
The main comparisons of sensor sizes are with APS-C or ‘cropped’ sensors and those considered to be ‘full frame’ / 35mm equivalent.
As APS-C sensors are physically smaller than 35mm we have a reduced field of view in comparison. A smaller sensor with a common crop factor of 1.5x means a 400mm lens will see the equivalent field of view as a 600mm lens on a full frame camera.
Any Other Considerations?
Yes, technique and perspective
Telephoto lenses are less forgiving than wider angle or ‘standard’ focal length lenses. Depth of field is often a lot shallower and they may be significantly heavier and more susceptible to vibrations. A solid tripod and tripod head are often required. In-built lens stability is often very effective at combating shake or allowing you to use slower shutter speeds and maintain sharpness – but not always, especially if your subject is moving.
Perspective distortion can also vary greatly as longer focal length lenses are used. A telephoto lens gives the impression that near and more distant objects seem closer together than they actually are.