Distortion is an aberration in the photo results that usually occurs with wide lenses or telephoto lenses. On wide lenses it is known as barrel distortion, on telephoto lenses it is known as pincushion distortion.
Barrel distortion (convexity) on wide lenses is between 10-16mm
Source : http://www.infofotografi.com/
Barrel distortion (top) ; After repair (below)
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Usually barrel distortion on lenses that are not too wide is still not too severe. For landscape photos, you can leave it alone, according to taste. But if you take photos of architecture or buildings, it can be quite disturbing because there is a pattern of lines that should be perpendicular and become curved.
Pincushion distortion (concave)
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So how do you solve it?
You can activate the auto correction lens on your camera if you have it. But the downside is that you can't shoot in RAW mode. Apart from that, you can also fix it using software. For example, in Adobe Lightroom, you can use lens correction . There are quite a lot of lens choices, except for the types of lenses that are too old school, like those from the 70s, which are usually not available. You just have to activate "enable profile correction" and your photos will be corrected automatically.
Source : http://www.infofotografi.com/
Source : http://www.infofotografi.com/
You need to remember that when taking photos, leave a little distance so that when the photo is corrected, important parts of your photo are not cut off.