Tuesday, November 2, 2010

Reflections Part 1

First, I apologize again to anyone who was looking for new content here. I made a promise I couldn't keep, and I'll not do that again. Nevertheless, I will try to add new content as time permits.

Today I'd like to start the first of several posts on light reflection. For me, it is the most important of all lighting concepts. I'll try to keep the technical stuff to a minimum, using visual aids to make the major points.

Reflections come in basically two forms: direct and diffuse. A direct reflection is a reflection of the light source, and is also called a specular reflection. Mirrored surfaces, for example, produce primarily direct reflections. A diffuse reflection, also known as an indirect reflection, is created when light striking a surface is scattered in a variety of directions. Matte paper, and talcum powder are two examples of diffuse reflectors. Keep in mind that no surface is a perfect direct or diffuse reflector, rather most surfaces produce a combination of both direct and indirect reflection. The differences between the two reflection types are shown diagrammatically below.

The diagram above shows the setup for a little experiment which uses a highly polished steel sheet as a direct reflector and a piece of white foam-core board as a diffuse reflector. The series of photos below shows the results for the two surfaces and two lighting positions. Note that the white board reflects back light similarly regardless of light position, while the polished plate produces strikingly different results. The direct reflector here acts in a kind of on-or-off fashion, either you see a reflection or you don't.

In the following posts, we'll dig a bit deeper into reflections and examine how they can affect our portraiture.

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