Usually, if you use a wide lens, there will be distortion in your photos. There are two types of distortion, optical and perspective distortion. Usually the cause of optical distortion is the optical design of the lens, which is often called lens distortion. Meanwhile, perspective distortion is usually caused by the position of the camera towards the subject. Let's discuss them one by one..
1. Optical distortion
Distortion occurs due to deformation which makes straight lines curved, many are known as curvilinear. Optical distortion is caused by lens errors. Several types of optical distortion:
a. Zero distortion
In general, every lens has a distortion effect. But good lenses have lens elements that can help reduce distortion significantly.
b. Barrel distortion
Barrel distortion usually looks like convex, straight lines curving outward to form a barrel. This usually occurs with wide lenses because the lens' viewing angle is far and wider than the size of the image sensor.
This distortion occurs in almost all wide lenses, fixed/prime lenses and zoom lenses with short focal lengths. The resulting distortion effect varies depending on the distance of the camera to the object. Some lenses, such as the Nikon 14-24mm f/2.8G, are equipped with distortion compensation elements, but this makes the lens heavier and larger in size. That's why wide angle lenses are usually bigger and heavier than regular lenses.
c. Pincushion distortion
This distortion is the opposite of barrel distortion, which is curved inward (concave). Usually happens a lot with telephoto lenses. Because the viewing angle is smaller than the size of the image sensor, it needs to be pulled to adjust.
This distortion is very common, even pro lenses such as the Nikon 80-400mm VR still experience distortion, barrel distortion at 18mm, and starting to experience pincushion distortion at 28mm to 300mm. This distortion can be corrected by editing using Photoshop or Lightroom.
d. Moustache distortion
Moustache distortion is also known as wavy distortion which is a combination of barrel and pincushion distortion.
This distortion cannot be helped by using the editing process in Photoshop or Lightroom. If you try to edit the photo, such as the barrel and pincushion, it will make the curved corners even worse.
2. Perspective Distortion
Perspective distortion has nothing to do with lens optics, but if we position an object too close to the camera it will produce perspective distortion. For example, when you photograph a small child close to the head, the child's head will look bigger and the feet will be smaller.
The photo was taken using a focal length of 18mm with the camera very close to the object so that the child's head looks bigger. It can also be done when you take pictures at a low angle. So, perspective distortion can be influenced by the distance of the camera to the object as well as the angle at which the image is taken.