The advantage of interchangeable lens cameras like DSLRs and mirrorless cameras is that you can change lenses for different kinds of photography. There are many different types of lenses, often with specific names.
Lenses are usually characterised or grouped by their focal length. It might be more useful to use their angle of view instead, but focal length is the measurement which has stuck and is universally recognised amongst photographers.
Using focal length to describe a type of lens came about from the widespread use of 35mm cameras (now full frame cameras). It doesn’t work so well with cameras that have different sensor sizes because this affects the angle of view of the lens. This is why photographers and camera makers often quote ‘effective focal lengths’ for cameras with smaller sensors. All the lens type descriptions below use ‘effective’ focal lengths.
Zoom lenses vs primes
Most people use zoom lenses. The ability to change the angle of view and subject magnification is so convenient that zoom lenses are a standard choice for many kinds of photography.
Prime lenses have a fixed focal length. You can’t zoom in and out, so if you want to change the size of your subject in the frame you have to physically move closer or further away.
This sounds like a major disadvantage for prime lenses, but the do have some advantages too. In fact, prime lenses are making something of a comeback.
Zoom lenses are big and heavy, and the best quality lenses are expensive too. Prime lenses are usually smaller and lighter. They may not necessarily be cheaper, but that’s because they are often designed for maximum optical quality. It’s easier to get high quality results from the simpler optical design of a prime lens than it is from a zoom.
Prime lenses are ‘faster’ – in other words they have a higher maximum aperture. This means you can use faster shutter speeds in low light. A wider maximum aperture also means the opportunity to throw backgrounds out of focus and concentrate attention on your subject.
Many photographers also find prime lenses make them shoot more creatively. Prime lenses force you to walk up to and around your subjects rather than just shooting from a single position and using the zoom to fill the frame.
Standard lenses and what they can do
A ‘standard lens’ is one that closely matches the normal human field of vision. When cameras came with fixed focal length lenses, the ‘standard lens’ was a 50mm prime lens.
Now, photographers use a ‘standard zoom’ to cover a range of focal lengths both wider and longer than 50mm. This will often be the ‘kit lens’ that comes with the camera.
A standard zoom might typically have a focal range of 28-70mm, or 24-70mm or 24-105mm even. At their widest zoom setting, they offer a wideangle view and at their longest zoom setting they are equivalent to a short telephoto lens. They are pretty versatile, but you will need other lenses for particular subjects.
‘Pancake lenses’ are standard zooms (or prime lenses) which are specially engineered to be as thin as possible. They’re ideal for small cameras used when travelling light or for carrying in small bags or pockets.
Wideangle lenses and their uses
Wideangle lenses – obviously – take in a wider angle of view than regular lenses. There are no hard and fast rules, but it’s generally agreed that a 35mm lens is a ‘moderate wideangle’ a 28mm lens is a genuine wideangle and by the time you get to focal lengths as short as 20mm or less, you are into ultra-wideangle territory.
It’s possible to get ultra-wideangle lenses with a focal length of as little as 11-12mm, and produce extremely pronounced perspectives and incredibly wide angles of view. This is just about the limit for current optical technology, however, for capturing ‘rectilinear’ images where straight lines stay straight.
There are lenses that are even wider than this. So-called ‘fisheye lenses’ no longer make any attempt to reproduce straight lines and instead create a distinctive bowl-like distortion effect. It’s a striking visual effect for some subjects, but not one you’d want to use all the time.
Perspective control and tilt shift lenses
Wideangle lenses enable you to get much closer to a subject than normal and still get it all in the frame, but this can bring its own problems. Very often you will need to tilt the camera to capture the whole of your subject, and this produces perspective distortion. The most common type is the converging verticals effect you get with tall buildings.
This can be corrected with the use of a perspective control lens (or ‘PC lens’). These are expensive and specialised lenses which offer a vertical and horizontal ‘shift’ movement relative to the camera body. If you ‘shift’ the lens upwards, you can get a tall building into the frame without tilting the camera.
These are sometimes called ‘tilt shift’ lenses because you can also tilt the lens relative to the camera body. This is used for depth of field control. By tilting the lens one way you can increase the depth of field for an object at an angle to the camera, or you can tilt the lens the other way to make the depth of field much shallower.
This exaggerated shallow depth of field effect is very popular for recreating a retro look or the illusion that you’re looking at a miniature version of the world (the angle and the subject have to be right for this illusion to be convincing).
Telephoto lenses and their uses
Most photographers start off with a telephoto lens as the first additional lens for their camera system. It’s an obvious choice because a telephoto lets you fill the frame with subjects you can’t normally get close to, such as athletes or animals.
With wideangle lenses, the shorter the focal length, the wider the angle of view. With telephotos, the longer the focal length, the greater the magnification.
A telephoto zoom in the 70-300mm range is a popular first choice, offering a lot more magnification than a standard zoom but without too much expense. These lenses have variable maximum apertures, however, so at full zoom the maximum aperture is smaller.
For this reason, experts and professionals will often pay extra for a 70-200mm f/2.8 lens. This has a shorter zoom range but a constant f/2.8 maximum aperture. This is better for faster shutter speeds and blurring backgrounds.
These lenses may not get you close enough to some subjects, which is where you may need a super-telephoto in the range 100-400mm or 150-600mm. These lenses are bigger, heavier. And more expensive, and they will have variable maximum apertures.
The alternative is a fast telephoto prime lens with a fixed focal length but a wider maximum aperture, such as a 300mm f/4 or a 500mm f/5.6. These are very expensive, however, and designed for professional use.
Teleconverters for extending your range
Some telephoto lenses can be used with teleconverters. These fit between the lens and the camera body and multiply the focal length of the lens by 1.4x or 2x. The drawback is that they reduce the maximum aperture by 1 stop and 2 stops respectively.
Portrait lenses for people
Portrait lenses are a specialised kind of telephoto. They have a focal length of 85mm (sometimes slightly longer) and a very wide maximum aperture of f/1.8, f/1.4 or even f/1.2.
They’re called ‘portrait’ lenses because they give the ideal working distance for portrait shots to get flattering facial perspectives without any distortion, with a wide maximum aperture for blurring backgrounds.
Macro lenses for close-ups
Macro lenses are fixed focal length prime lenses which have been specially designed for ultra-close-up photography. Not only do they focus closer than regular lenses, they have optical designs which are specially optimised for close shooting distances.
Macro lenses are typically around 90mm in focal length with an aperture of f/2.8 or thereabouts. Longer focal length lenses will let you shoot timid subjects from further away, and with shorter focal lengths you will have to get closer to your subject.