If the corners or edges of your images sometimes appear much darker than the rest of the frame, vignetting is probably the culprit. Vignetting is aberration that occurs when less light reaches the corners of the camera’s sensor, and in the resulting image these areas are more under-exposed (or darker) than the centre.
Vignetting is common with certain lenses – especially wide-angle zooms – and when using wide apertures. It can also be caused by a physical obstruction, most typically a filter, filter holder or ill-fitted lens hood, which prevents light from reaching the corners of the frame.
If you’re having problems with vignetting, here are some solutions.
How to correct vignetting
Reduce the aperture
Vignetting is most apparent when shooting at wide apertures such as f/4 or f/5.6, so the easiest way to reduce it is to set a smaller aperture of, say, f/8, f/11 or f/16. But be aware that the shutter speed will become slower, so you may need to increase the ISO or use a tripod to prevent camera shake.
Take care with filters
Wide-angle lenses are prone to vignetting, and it’s particularly noticeable with filters fitted. Use thin screw-in filters and remove UV filters. Remove filter holders and hold the filter flush against the lens instead. Avoid the widest focal length of wide-angle zooms.
Fix vignetting in Photoshop
If you can’t avoid vignetting as you shoot, use Photoshop or other editing software to fix the problem. Shoot in raw and process in Adobe Camera Raw, using the slider in the Lens Profile Corrections panel to remove vignetting. If vignetting is bad, you may need to crop the image too.
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