Simply put, a wide angle lens is one which has a wider angle of view than a normal lens. This allows you to fit more into the frame, or to get closer to your subject without chopping the edges off.
They are available in a variety of focal lengths. These range from medium wide angles, which give a slightly wider field of view than normal, to extreme wide angles which distort and warp the image in all sorts of intriguing, abstract ways.
Wide angle lenses are ideal for photographing expansive landscapes, cramped interiors, and subjects which wouldn't fit into the field of view of a normal lens, such as a large building shot at relatively close range. More severe wide angles are used to give an artistic, dynamic edge to a shot, such as in extreme sports photography.
Any camera lens with a focal length of less than 35mm is considered wide angle. A lens with a focal length of less than around 24mm is considered an ultra wide angle lens - these are commonly called fisheye lenses because of the extreme angle of view.
Common focal lengths are 35mm, 28mm, 24mm, 21mm, 17mm, and 14mm, although some manufacturers make lenses which go down as far as 6mm or even lower.
You can buy wide angle lenses in both fixed focal length (prime) and zoom formats. Once you get below about 28mm, prime lenses tend to have the better image quality in terms of sharpness, but zooms offer more flexibility.
The focal lengths mentioned above all apply to a full-frame camera with a 35mm sensor or film. For cameras with smaller sensors, the angle of view won't be as extreme. To find the equivalent focal length on your camera, you need to multiply the lens's focal length by the camera's crop factor.
Because cameras with smaller sensors reduce the wide-angle effect, many manufacturers sell lenses with an even shorter focal length than normal, to compensate and give you a true wide angle view.
Because of their ability to capture a large area, wide angle lenses affect your image's perspective:
When using a wide angle lens, you'll often be positioned very close to your subject. This makes foreground objects appear very large in the frame, and distant objects very small. Wide angle lenses also exaggerate the distance between objects, making subjects at moderate and far distances seem further away than they really are.
You can use this effect to emphasise foreground subjects, isolating them from the background and making them fill the frame for added impact. However, the wide angle still allows you to capture plenty of background detail in your photo, which can be useful for adding interest and context to the main subject.
Because of the exaggerrated difference in size between near and far objects, wide angle lenses tend to produce a distorted image, with subjects appearing elongated.
This can give your photos a dynamic, abstract feel, but it can also produce some unwanted effects. For example, if you photograph a person's face through a wide angle lens, their features will appear to bulge and bloat - interesting but not particularly flattering!
Rectilinear vs Curvilinear Construction
Many wide angle lenses are constructed to produce what is known as a "rectilinear" image. This means that straight lines are kept more or less straight in the final image, rather than being bent and distorted. However, with these types of lenses, subjects near the edge of the frame tend to be stretched unnaturally.
For super wide angle lenses, such as fisheye lenses, this stretching becomes very noticeable and distracting, so manufacturers tend to use a "curvilinear" construction instead. Curvilinear lenses don't have the same edge distortion than rectilinear lenses do, but instead they cause straight lines to curve, an effect known as "barrel distortion".
Depth of Field
Wide angle lenses have a greater apparent depth of field because they cover a wider viewing angle. This makes them great for photographing scenes where you have subjects at different distances, such as a landscape with animals in the foreground and mountains in the background, and want them all to be sharp.
The downside to this is that you cannot isolate your subject by using depth of field to blur the background. Instead, you need to pay more attention when you frame your shot, choosing a composition with an uncluttered background.
Several factors affect the image quality produced by a wide angle lens:
Because of their wide viewing angle and large apparent depth of field, wide angle lenses generally produce photos which are sharp throughout. However, this can be slightly reduced when shooting at very wide apertures, as with any lens. At very narrow apertures, light diffraction can also cause edges to appear slightly fuzzy.
To ensure maximum sharpness throughout your scene, aim to use an aperture in the middle of the lens's range wherever possible. This may mean using a slow shutter speed, so be sure to use a tripod to reduce blurring from camera shake.
In any scene, light levels will naturally vary in different areas. For example, the sky may be bright, while the ground is relatively dark. This becomes very apparent when shooting at such wide angles, and can result in photos which are underexposed in some areas and overexposed in others.
You should be aware of this when framing your scene, and be careful to expose the important areas properly, sacrificing detail in less important areas. A graduated ND filter can be useful in balancing the brightness of the sky and foreground.
Because of the wide area covered, it is also common for the sun to be included in your shots, and this can lead to lens flare or incorrect exposure. Lens hoods aren't a practical solution because they can block part of the view.
Most wide angle lens manufacturers recognise this problem and build their lenses to minimise lens flare, but they are not perfect, so you should do your best to keep the sun out of the frame, or hide it behind something in the scene.
A vignette is a darkening of the image towards the edges and corners. It is is common in all wide angle lenses, although it is particularly noticeable in the cheaper ones.
There's no real way to avoid it, so it is important to try out any lens before buying, to see how much it is affected. Thankfully, modern software packages such as Photoshop have made it easy to remove this effect from digital photos.
Capturing such a wide angle can produce unwanted effects from filters. This is particularly true for polarizing filters, where the effect depends on the angle between the lens and the sun. With a wide angle lens, this angle can vary greatly within a single shot, and your photos will show a noticeable variation in brightness from one side to the other.
Where possible, it is best to avoid using filters with wide angle lenses. If you do use them, keep a close eye on the effect they're producing.
A cheaper alternative to a proper wide angle lens is a wide angle conversion lens, also known as a wide angle converter. These are a type of accessory lens which screw onto the filter thread of your existing lenses. They and act in the opposite way to a magnifying glass, shrinking the objects in a scene and allowing you to see a wider angle.
While these are much cheaper than wide angle lenses, the optical quality is generally quite poor. They also don't accept filters, require you to focus manually, suffer from lens flare, and can stop the lens from zooming.
Because of these drawbacks, wide converters are a fun toy to play and experiment with, but should not be seen as a serious alternative to a wide angle lens.
Buying a Wide Angle Lens
If you shoot using a Canon or Nikon camera, then the best quality lenses are those made by the same manufacturer. However, these tend to be the most expensive, so if you are on a budget you should also consider the excellent alternatives made by other reputable companies like Tokina, Sigma, and Tamron.
Before buying, read online reviews and ask opinions from other owners. If possible, visit a store and try the lens out for yourself. Once you've made your decision, you can find some excellent prices online at places like Amazon and Adorama.
Cover image by Alex Holyoake.