My Review Everything post was intended to highlight my frequent neglect of ensuring my captured images are exactly what I need to create the image I have in my head. I brought up the image of the Wildcat Student Center and the lens flare that I inadvertently captured. I was so excited about the water puddle and its reflection that I failed to notice the flare in the opposite corner of the image. One of the comments (Thank you Dawn!) asked if I could explain lens flare a little more.
Lens flare is a phenomenon of the camera lens. There are various types of flare, some that can be used within your image and some that are less desirable. I turned to this article from Cambridge in Color to gather some appropriate descriptions and images to help me explain. Before I dive into this topic let me show a few images of mine where I used the flare to my advantage.
In the first image I was able to get the camera parallel to the intense light source (the sun) and the flare, or star burst looking light was actually intentional. This is less of a stray light flare and more a flare due to the aperture of the lens. It was definitely something I was trying to achieve.
In the second image I was once again going for the star burst light rays with the sun but due to the angle of the lens some light was reflected inside causing the colored circles emanating from the sun above the bottom layer of clouds. Re-positioning the lens might have minimized this effect but would have changed my composition and I think the impact of this image.
Borrowing from the Cambridge in Color article:
How it Happens
All but the simplest cameras contain lenses which are actually comprised of several “lens elements.” Lens flare is caused by non-image light which does not pass (refract) directly along its intended path, but instead reflects internally on lens elements any number of times (back and forth) before finally reaching the film or digital sensor.
Lens elements often contain some type of anti-reflective coating which aims to minimize flare, however no multi-element lens eliminates it entirely. Light sources will still reflect a small fraction of their light, and this reflected light becomes visible as flare in regions where it becomes comparable in intensity to the refracted light (created by the actual image). Flare which appears as polygonal shapes is caused by light which reflects off the inside edges of the lens aperture (diaphragm), shown above.
Reducing Flare with Lens Hoods
A good lens hood can nearly eliminate flare caused by stray light from outside the angle of view. Ensure that this hood has a completely non-reflective inner surface, such as felt, and that there are no regions which have rubbed off. Although using a lens hood may appear to be a simple solution, in reality most lens hoods do not extend far enough to block all stray light. This is particularly problematic when using 35 mm lenses on a digital SLR camera with a “crop factor,” because these lens hoods were made for the greater angle of view. In addition, hoods for zoom lenses can only be designed to block all stray light at the widest focal length.
I will not repeat the whole article and would encourage you to read it through if you wish to minimize or even enhance lens flare in your images. When done properly a good flare can ‘plus’ an image. In the case of my Wildcat Student Center image I felt that it was a distraction, although several readers confessed to not noticing the flare until I pointed it out. Hopefully my nickel tour of lens flare has been helpful.