Specular Reflections

I thought this image is quite interesting and illustrates a useful property of light that can be used to good effect in photographs. You see in the above image, that the light from the window is directly illuminating the floor, creating a sharp image of the window. You will also see that in addition to this image of the window, There is another fainter image of the window on the floor to the right.

The second image is what is called a specular reflection. The window is reflected in the floor because the floor s glossy, but because the surface of the floor is quite bumpy, the light is reflected off in lots of different directions and the reflection is rendered rather fuzzy looking.

You can take advantage of this specular reflection to get two light sources out of one. You can illuminate your subject with direct light from the window and through careful choice of camera angles place the specular reflection in the image.

Using a fixed light source like a window can be a little inconvenient but if you have a strobe and a white shoot through umbrella you can do this anywhere where you have a reflective surface to bounce the specular reflection off. The smoother the surface, the more well defined the reflection.

Here on strobist.com David Hobby put together a great tutorial on using specular highlights as a background element in portraits. This technique looks like magic until you figure out what is going on. Its something you can use with strobe lights, but also if you look for opportunities its something you might be able to use even with ambient light.