Light falloff may increase because an image is exposed more at the center of the frame than at the corners. The distance light has to travel from the lens to the sensor is greater at the edges than it is at the center and, therefore, less light reaches the sensor from the lens at those more oblique angles. In addition, some of the outer off-axis light is restricted by the lens barrel, which is known as vignetting. This effect is most common in wide-angle lenses that are used at the initial aperture (i.e., wide-open). Falloff due to vignetting can usually be reduced by stopping down.
- If you have a profile for your lens, set the amount to 100% to result in a completely flat and even-looking image.
- Alternatively, use a generic profile and manually set the desired amount with care. Values higher than 100% are possible and increase the effect of the correction.
- The setting can be saved as a component of a User Preset and applied to multiple images.