In photography, a vignette refers to a reduction of the brightness or saturation toward the edge compared to the centre of an image. It is also used to mask certain areas of a negative before copying. Photographs that show a vignetting effect are often referred to as vignettes themselves. A vignette that unintentionally appears on an image is caused by less light reaching the sensor towards the edge of the image. While the centre of the image is correctly exposed, the peripheral areas and corners of the image appear underexposed and show as slightly darkened. However, this effect can also be added to influence the mood of the picture.
Vignetting often occurs naturally when using wide-angle lenses. With these lenses, the light passing through the edge must travel a further distance than the centre. The light rays that take a longer path have less energy when they reach the sensor, which causes a darkening in the edge area. Some wide-angle lenses have built-in filters that reduce or eliminate this effect. These special filters darken the centre of the image so that the brightness is balanced out on the final exposure. A vignetting can also occur when the edges of apertures or filters slightly block the image field. This causes shading at the edges in the form of a vignette. Using the correct filters and shutters and ensuring they are mounted correctly can eliminate any unintentional vignettes. Tulip-shaped lens hoods, for example, have cut-outs at the corners, as this is where vignetting first becomes noticeable.
Vignetting effects also often occur naturally when using cheaper lenses. They do not allow even light to the sensor, especially in low light. If the diameter of the lens is too small for the selected shooting format, the light intensity at the edges of the image will also be reduced. In this case, vignetting can be prevented by using a smaller format.
Vignetting can often be reduced or even eliminated by stopping down the aperture. When shooting with a film camera, vignettes can be mitigated by removing light obstructions from the edges and corners. Editing software can help to brighten certain areas to reduce or eliminate any vignette on digital photos. It is also possible to add a vignette effect in post-processing.
Some photographers use vignetting to add a certain effect to an image, for example, to give photos a retro effect. Vignetting is often used in creative and experimental photography known as Lomography. A vignette helps point the viewer to the centre of an image by darkening the edges. This is a great tool to emphasise a subject and help reduce unwanted distractions around the edges.