Photograph of NASA lunar lander containing lens flare. Besides the obvious flare around the Sun, the light artifacts at the bottom right are also caused by flare.

Lens flare typically manifests in images or views through optical systems as several starbursts, rings, or spheres arrayed in a sequence across the image or view. It is caused by the scattering and internal reflection and refraction of bright light in the optical components of complex lens systems, for example a camera. Typically this will become prominent when pointing a device such as a camera too near a bright source of light. Lens flare patterns will angle across the scene and change location with the camera's movement tracking with the light position and fading as the camera points away from the bright light until it causes no flare at all.

Lens flare is extremely difficult to control when a bright light source like the sun is just outside the frame.

When a bright light source is shining on the lens but not in its field of view, lens flare tends to be a bright haze that washes out the image and reduces contrast. This can often be avoided by shading the lens, either with a lens shade that attaches to the lens or by holding an object or hand between the light source and the lens. In a studio, a gobo can be attached to the lighting to keep it from shining on the camera.

Artificial lens flare is a common effect in various graphics editing programs, although in the graphic design community it is almost universally condemned.