Manifestation
The spatial distribution of the lens flare typically manifests as several starbursts, rings, or circles in a row across the image or view. Lens flare patterns typically spread widely across the scene and change location with the camera's movement relative to light sources, tracking with the light position and fading as the camera points away from the bright light until it causes no flare at all. The specific spatial distribution of the flare depends on the shape of the aperture of the image formation elements. For example, if the lens has a 6-bladed aperture, the flare may have a hexagonal pattern.
Such internal scattering is also present in the human eye, and manifests in an unwanted veiling glare most obvious when viewing very bright lights or highly reflective surfaces. In some situations, eyelashes can also create flare-like irregularities, although these are technically diffraction artifacts.
When a bright light source is shining on the lens but not in its field of view, lens flare appears as a haze that washes out the image and reduces contrast. This can be avoided by shading the lens (the purpose for which lens hoods are designed). In a studio, a gobo or set of barn doors can be attached to the lighting to keep it from shining on the camera. Modern lenses use lens coatings to reduce the amount of reflection and minimize flare.
When using an anamorphic lens, as is common in analog cinematography, lens flare can manifest itself as a horizontal lines. This is most commonly seen in car headlights in a dark scene, and may be desired as part of the "film look".
Read more about this topic: Lens Flare