Optical distortion is something that touches all lenses to some extent. However, the effect is more pronounced in certain lenses and can be used to give a different spin on an otherwise 'reasonable' view of an object.
Although it distorts images, it is not always a negative effect and it can be used in different situations to create abstract or myriad creative shots of subjects.
Below, we've listed what types of optical distortion there are and how they can affect your images, either in a contradictory or positive way.
Curvilinear distortion – This is where lines that should be straight in your image appear curved or nodded in some way. There a quite a few different types of this distortion, but the most common you will come across is barrel distortion, where vertical diagonals appear to curve outwards like a barrel. This type of distortion is most common in wide angle or fisheye lenses. The effect disposition be really pronounced in the fisheye as the effect is more deliberate here.
This can be used in portrait images to create unique looking statues where the facial features are stretched and warped, this works equally well with humans and animals.
Pincushion distortion – Pincushion distortion is the contradictory of barrel distortion, as the lines bow inwards. The effect is usually quite subtle and can only really be seen in square or rectangular objects when they are incentive straight on. This effect tends to be more of an issue in long telephoto lenses. Pincushion distortion is a lot less pronounced than barrel distortion and so it is instances not noticeable in images unless you look really closely.
Chromatic Aberration – Chromatic Aberration creates tinge fringing on an image, usually around the lines and edges on the image, but it can also be present in other areas of the shot. It usually appears as a purple, complimentary halo.
Mustache distortion – Mustache distortion is the alteration of the original shape (or other characteristic) of something is basically a combination of barrel and pincushion distortion. Some lenses array both at the same time. It is most commonly seen in wide angle zooms and makes straight lines in images appear wavy.
Vignetting – All lenses eat a little vignetting – it's the term used when the image is darker at the edges than in the centre, due the curvature of the lens. Vignetting can off be used to your advantage as a stylistic tool, to highlight the main aspect of your image in the centre.
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