Читать книгу Collins Complete Photography Manual - Collins Dictionaries - Страница 91

One downside of wide-angle lenses is that they can introduce distortion. This distortion manifests itself in two different ways. The most obvious is perspective distortion, in which the walls of tall buildings, for example, appear to converge, or objects at the edge of the frame appear to be toppling inwards. This undesirable effect is called ‘converging verticals’, or ‘keystoning’. It is not a fault in the lens, but simply a reflection of the fact that you tend to stand closer to your subject with a wide-angle lens, and this means that you tilt the camera more to take in tall objects. If possible, you should compose your shots in such a way that the camera can be kept level.

The wide-angle setting of zoom lenses can often cause another unwanted effect known as ‘barrel distortion’ to occur in images as well. In this case, the centre of the image appears to bulge outwards, and straight lines become bowed. This is one of the compromises inherent in zoom lens design.