Vignetting

Vignetting refers to a loss of imaging area at the corner or peripherals of the frame. There are three reasons to explain how vignetting can occur:

Optical Vignetting – This is due to using a large aperture such as f/1.4 but this can be corrected by reducing the size of the aperture. The image resulted is a gradual darkening towards the centre.

Mechanical Vignetting – This is caused by light being blocked by external objects such as stacked filters, large hood attached to the len. The image resulted is a small dark area near the corner of the frame. To correct this, simply remove any obstruction to the len.

Natural Lighting – This is due to a law known as cos fourth law of illumination falloff. This falloff is proportional to the fourth power of cosine of the angle at which the light strikes the sensor. This form of vignetting cannot be cured by stopping down the len. vignetting often interrupt or distract but does not necessary mean it is when can be used draw viewer to centre of the frame>

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