By : Nikon School Blog | 17 Mar, 2016 |
Ever wondered why certain images look great while some, taken at the same settings, look unimpressive, distorted, funny, even weird at times? In an era when most people are starting photography with zoom lenses, the importance of learning the relation between focal length and perspective is often getting lost.
Put simply, focal length tells photographers how much area of a scene they can view through a lens, and also, how much the image will be magnified. It is measured in millimeters, and denoted by 'mm'. Often, photographers simply mention the number to denote a lens, like, a 35, or a 50.
Each focal length results in a certain perspective. Perspective is how the objects in the frame appear, and how the different elements of the frame appear with respect to each other. Understanding perspective is of utmost importance for any photographer.
Short focal lengths stretch the scene and create distortions, particularly noticeable at the edges of the frame. If people or straight lines like pillars or buildings are kept at the edges, the effect is more pronounced. Sometimes, in group photographs, people placed at the edges of the frame often get distorted.
Short focal lengths also distort perspective. They create an illusion of increased distance between the foreground and background and more of the background is visible. This is useful if a lot of background is to be shown in a relatively small area, but can pose problems if there are a lot of unwanted elements in the frame.
Short focal lengths up to 28mm are generally suited for landscape and street photography, but are not recommended for portraiture or going close to still life subjects like flowers, fruits, objects etc, as they will distort the appearance of the subject. Sometimes, this is done deliberately to create a distorted or funny perspective.
50mm is considered to be a normal lens. This is because this focal length is similar to the human eye's perspective. What we see is the same as what this lens shows. This lens in its ideal form has no distortion, and things look as they do in reality. This makes it the best lens for portraiture and subjects like statues, flowers, objects etc.
For Nikon's DX format, the 35mm acts as normal.
Perspective changes at higher focal lengths as well. High focal lengths cause reduced coverage of the background. This is very useful to remove clutter from the frame, but can flatten perspective, causing foreground and background to appear merged. Background subjects also appear larger.
At 200mm or higher, we can notice that a subject looks bigger than in reality.
A zoom lens has multiple focal lengths, and perspective changes at each focal length. Beware of perspective distortion the next time you zoom in or out.