Unit One: Opticks

Diagram of Camera ObscuraDiagram of Camera ObscuraHere are two diagrams of the camera obscura, one found in the work of Renaissance natural philosopher Gemma Frisius and the other a copy of Frisius’ diagram by a seventh grader.

Description

Renaissance exploration of the camera obscura touched on philosophy, physics and biology, and art. The physics, of course, tried to discover what light is as well as how it works. This led to the inference that the eye is itself a type of camera obscura. Philosophically, the concept of light is indeed rich. (See in particular, Arthur Zajonc, Catching the Light: The Entwined History of Light and Mind, Oxford University Press, 1993. In art, the camera obscura enabled artists to explore more deeply the problem of perspective and representation. It was a tool for drawing more accurately the world around them–but it was tool used in secrecy (Vermeer’s use of the camera obscura was not discovered until the 20th century!)

Demonstration:

The Latin phrase camera obscura means literally a “dark chamber.” In this demonstration, it is important to create a space, possibly–even preferably–the classroom, in which almost total darkness is created. This can be done by covering the windows with black paper (I recommend at least two layers) making sure that not even a crack of light shows through. Likewise, cracks around doors where even a tiny bit of light might come through. Once the room has been secured in this way, a few holes should be cut into black paper covering the windows (suggested sizes: dime-sized, quarter-sized, hole-punch size). These holes should be fitted with covers (black paper works well). Try to make the holes as perfectly round as possible.

Materials:

black paper, duct tape, tracing paper, a movie screen (not absolutely necessary)

Procedure:

Once the students are seated in the room turn off the lights and give them a moment to accustom their eyes to the darkness. Then uncover the largest hole (now known as an aperture). After a few moments, the students may begin to notice things: shadows moving across the ceiling and walls (it depends on the classroom’s orientation to the out-of-doors). Change apertures, and ask the students to pay attention to the images. Once they figure out what is happening it is quite an astounding experience for them–and for the teacher. The extra work is worth the effort.

The history of the camera obscura

Though the ancient Greeks may have known about the camera obscura, it is with the Renaissance that this technology really moves forward. The Belgian polymath Gemma Frisius was the first person to publish his work with the camera obscura. Later the painter Jan Vermeer is thought to have used the camera obscura in his work. (An interesting side note is about the incredible advances in lens grinding and polishing that were going on in the Low Countries–the Netherlands, Belgium–during this time). Vermeer’s work led right up to the invention of the modern photographic camera.

Suggested artistic activities:

  • Drawing a diagram of Gemma Frisius’s camera obscura (see item)
  • Build a tabletop camera obscura as a class project or as an individual project.
  • Use the camera obscura to draft a picture, as Vermeer would have done.

The pinhole camera

The next logical step in working with this technology is the pinhole camera. Students can make one very easily using the simplest of materials. Here is a link: http://en.wikipedia.org/wiki/Pinhole_camera

Shadows and Light: The Mystery of the Mirror

Artwork showing how shadows can come out of mirrors

This image, taken from the work of a seventh grader, illustrates how a shadow seems to "come out" of a mirror. It is a wonderful exercise for disciplining students' powers of observation.

Shadows can appear to come out of a mirror given the right conditions. In this demonstration, students will awaken their sense of wonder and hone their skills of observation.

Set up a mirror or mirror board. Stand a small object (a cylinder, small statue or figurine, a large chess piece) a few inches from the center of the mirror with a lit candle at an angle to one side of the object (see illustration). Darken the room. The candle and object will be reflected in the mirror. Have students observe the light and shadows that are created. What is the source of the various shadows? Are you sure? (see item)

The Optical Bench

Diagram on optical lenses
You may want to lead students into the uses of lenses. A simple introduction is the optical bench (kits are available through most science education materials suppliers). The first telescopes were not enclosed in brass tubes but more like the optical bench.

Possible artistic activity:

Accurately draw the demonstration. Only by having students re-create the demonstration can you find whether they have accurately observed the phenomenon. Have them look again.

Print sources

Any good book on Vermeer’s work. Time-Life put out a decent one in the 1960s. There are many others.
Roberto Trostli, Physics Is Fun!: A Sourcebook for Teachers, Octavo, 1995.
Arthur Zajonc, Catching the Light: The Entwined History of Light and Mind, Oxford University Press, 1993.

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