Image Distortion – Affects the Shape of the Picture
Distortion is a lens defect which influences the shape of the picture without affecting the sharpness. The physical effect of such a defect is straight lines look bowed (bent) near the edge of the picture. There are to types of distortion – pincushion and barrel. In pincushion distortion, the straight lines are bent (bowed) in the inward direction while in barrel distortion the lines are bent (bowed) in the outward direction. Sometimes a mixture of both the types of distortion termed as moustache distortion is observed.
In such distortion at the centre of the picture, barrel distortion is observed and as one move to the picture periphery it turns out to be pincushion distortion. This distortion is observed in retrofocus lenses as well as with large range zooms. In photography, perspective distortion is the change produced in object and its surrounding that makes it look different from what they would look with normal focal length.
Distortion – Affects Shape of the Picture
Perspective distortion can be seen in situations where photographs are taken using a wide-angle of view. In such a case object near the lens appear large abnormally as compared to objects at a far off distance from the lens. Also when the distant shots are taken with a narrow-angle of view due to perspective distortion objects at a larger distance would appear exceptionally large. The two factors that create an impact for perspective distortion are the angle of view used by the camera to capture the image and the angle of view used to view the image of the subject.
The occurrence of perspective distortion is completely due to the angle of view used to capture the image of the subject in case photographs are taken from an ordinary distance. Perspective distortion is very distinct in the situation when you use the wide-angle lens at a short distance between the camera and the subject. The effect of this distortion can be overcome by using a moderate telephoto lens or lens with a long focus. These arrangements will flatten the picture.
The distortion is visible when photographs are viewed at a distance that equals their diagonal. If pictures are viewed at a closer distance thereby widening the presentation’s angle of view then distortion reduces. Another way is viewing pictures from a greater distance so that angle of view gets narrowed down. At a particular distance, the apparent distortion vanishes completely. In photography causes of the image, distortion is an error due to photographer, malfunction in-camera and use of unacceptable equipment.
Distortion – Affects Shape of the Picture
You can have a distortion in your photographs because of the incorrect aperture used in your camera, your hands not remaining steady or you not using right film speed in a given situation. If a scene has got excessive backlighting or you have used a wrong lens in your camera then also pictured gets distorted. It’s not that photographs from amateurs only are distorted; distortion can be found in photographs taken by professionals also. To clear distortion to a great extent image editing software is used. But the extent of distortion that can be cleared is dependent on the kind of distortion in the picture. Not all the distortions are fixed by software.
Next part will deal with image stabilization. How the quality of pictures taken will be fine by avoiding blurriness? The techniques used and precautions taken in taking quality pictures.
Tutorial Twenty one –Image stabilization – Necessary to overcome camera shake
Tutorial Nineteen – Mastering Vignetting – Photography Tutorial
Main Image Source : Pixabay
Also See : Picture Perfect – 100 Comments to make about Photographs
