The Path of Light
March 18, 2014
Sometimes choosing the right path to go down in life can be difficult, but for light it’s bit easier, it always travels in a straight line. Sure it can be absorbed and reflective but its path getting wherever it needs to go, is always going to be a straight one. I feel this basic principle of light is important to know if you want to understand how pinhole photography works. The diagram below shows how a pinhole camera light is reflected of something (such as a person) and flipped up-side down in the camera. The diagram on the left just shows two rays of light as a simple example of how works. But in reality it’s billions of tiny pin sized rays of light that make up the image in the camera.
Artists have know about this principle of and have made darkens rooms with a small hole in one side, “camera obscura” to help them draw and paint landscapes and portraits.
People sometimes ask me, “what if I make my pin hole the wrong size, will I still get an image?” Sure, but it might not be as sharp and “in focus” as it could be. The diagram below illustrates the light phenomenon called “Circles of Confusion“. I’m not going to go into explaining the details here, but I thought that it was another helpful diagram to illustrate what’s happening when you open and close the shutter of your pinhole camera.
The next diagram will show the intensity of light and how it effects the strength and definition of shadows. Notice how the shadow on the sunny side is sharp, clear and defined, where as the the shadow on the cloudy day is blur, soft and undefined. This why it would explain why is best to create pinhole photos when the sun is bright but create long defined shadows…either in the morning or afternoon. So when people ask me, “Chris, when is the best time to make pinhole exposures?” I always answer, in bright morning sunshine. I’ve read that photographic papers are most sensitive to this wavelength of light. Film is a little more forgiving than photographic paper and is fine to use any time of the day. So
Light is a wonderful phenomenon that most photographers like myself are in enamored with. And since photography is the study of light and the absence of it, this study is ongoing. The featured photo is a picture I took with my iPhone of light being casted on the window of my house. This image reminded me of something I read about early studies of light, where artist/philosophers observed how the sun when it shined through the leaves and branches of tree it created those shapes in shadows on the ground. This is how they knew that light must travel in a straight line.
Traveling in a straight line is fine for light, but for me, I don’t mind traveling a little more spontaneously. It is in those travels where I discover all sorts of people and things I never could have imagined before.
Happy St. Patricks Day! (What can I say, I’m Irish)