• Lens flare is something that photographers usually want to avoid.mountain,fog image by Andrzej Thiel from Fotolia.com
  
  Lens flare is a condition that often occurs in photographs when light goes where it is not supposed to go. When light that is not contributing to the image at hand enters the camera and hits the sensor or film, you get a flare in the photograph. These can wash out the color in the rest of the image, and show up as a polygonal object in the image.
  
  

The Sun

• One of the most common causes of lens flare is the sun. When shooting in direct sunlight, there is often sunlight that is not part of the image, and instead hits the lens directly. When this happens, the light starts to reflect between the different parts of the lens apparatus in the camera. Eventually, the lens reflects that excess light back onto the sensor in a digital camera, or onto the film in a film camera. This causes the flare artifacts and can wash out the color of the rest of the photograph. This can be limited or prevented using tools such as lens hoods, and by ensuring that you shoot only with lenses that have a good anti-reflective coating on them.
  
  

Artificial Light Sources

• Artificial light can cause lens flare just as easily as the sun can. For instance, when shooting at night, sources like headlights and street lamps can cause severe lens flare. Also, the flash on your own camera can cause lens flare. If you shoot with a flash and there are reflective objects in the frame, they can reflect the light from your flash back at the lens of the camera and cause a flare.
  
  

Backlighting

• When you are doing a professional shoot with lights, back-lighting is often desired to get interesting and dramatic shots. However, lighting a subject from the rear can quickly give a light source a direct line to your lens. No matter what type of pro lighting equipment might be used, if the light is leaking too much it can cause lens flare. This can be fought by using hoods, or by using reflector cards to reflect the light back on to a subject rather than placing it in direct back light.