It is caused when light strikes the lens and either causes the entire image to be fogged in appearance, or for a little row of polygons (the silhouette of the iris) to appear from the light hitting the surfaces of the many elements in the lens. It is solved by flagging the lens. [Go to source
Hot spot in a picture that is caused by direct light hitting the front element of the lens and reflecting through all the other glass elements in a lens.
a cool effect that occurs when internal refractions and refractions of incident light within the internals of a physical camera create bright patterns within the image
a natural phenomena that occurs when light is refracted many times by some sort of lens creating several images of geometric shapes to appear from a single light source
an image ( Background Investigation Online ) of
an image of the Sun reflecting back and forth between the lens elements of the camera
One of the tricks used to make a rendered image look more cinematic, seen as either rings of light that might come from reflections in a camera lens photographing the scene, or as a star-shaped glare around bright lights or flames.
In rendering, a simulation of several bright disks of light, of various sizes, extending in one direction from the light source. See also optical FX node.
If you take pictures while pointing your camera at a bright light like the sun you will get lens flare on your prints. Lens flare looks like a milky haze or a set of translucent discs overlaying the image. When taking your picture move your camera to make sure all bright light sources are left outside the viewfinder frame.
Lens flare is the light scattered in lens systems through generally unwanted image formation mechanisms, such as internal reflection and scattering from material inhomogeneities in the lens. These mechanisms differ from the intended image formation mechanism that depends on refraction of the image rays. For good optical systems and most images, flare is a secondary effect that is widely distributed across the image and thus not visible.