Hands-on Activity: Create a Pinhole Camera
Contributed by: Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder

 SummaryIn this activity, students construct their own pinhole camera to observe the behavior of light.
 Engineering Connection Relating science and/or math concept(s) to engineering Optical engineers need to understand how light rays work in order to design and create devices such as cameras, lasers and fiber optics.

 Contents
 Grade Level: 5 (3-5) Group Size: 1 Time Required: 20 minutes Activity Dependency :None Expendable Cost Per Group Keywords: My Rating: Avg Rating: Not Yet Rated.Teacher Experiences  |  Share your experience!

Related Curriculum :

 subject areas curricular units lessons

Educational Standards :

Longitudinal and Transverse Waves (Lesson 1), Wavelength and Amplitude (Lesson 2), Frequency (Lesson 3), Light (Lesson 6), Electromagnetic Waves (Lesson 7).

After this activity, students should be able to:
• Understand how light rays travel in straight lines are used in the processing of images.
• Use light rays to create a photographic image.
• Explain the basics of how a pinhole camera works.

Each group needs:

• 1 ½ gallon milk or juice carton (one per student)

To share with the entire class:

• Wax paper
• Pins
• 3-4 flashlights (for groups to test their cameras)

Students, this is the very last activity in our sound and light unit. You have all done a great job learning about sound and light and how engineers use their knowledge of sound and light to help improve our world. Today we are going to create something really neat – our own little cameras!
We learned in our lesson that light travels in straight lines and is inverted when it passes through a small hole. Today we are going to see this principal in action. Let's create a camera!

 Light ray: A beam of light with a small cross section. Ray diagram: A picture that predicts what an image will look like. The light rays in a ray diagram are drawn as straight lines. Pinhole camera: A simple camera that uses a pinhole to focus light on a surface behind it. All images created by a pinhole camera are inverted – the top becomes the bottom, left becomes right. This can also be called a camera obscura.

Background

Hundreds of years ago, images were etched in stone and later, with the advancement of modernization, onto various types of cloth or even paper. At this point, these images might actually have been paintings of landscapes, portraits or still life (such as a bowl of fruit or a plant). By definition, a picture is a precise copy of an image — a duplicate image, not just a redrawn copy.
So, before the creation of what we know today as digital cameras (or film cameras, which are still widely in use), what did people do to have a copy of a certain image? Well, in the mid 1600s, a dark room, also know as a dark chamber or camera obscura, was cleverly used to transfer an outside image onto paper inside a room. To explain, a large room has a hole in one of the walls. When lights enters the small hole, the outside image is reflected onto the opposite wall. An artist, standing in the room, would then draw the image as it appears on the wall onto paper.
Then in the mid 1800s, the use of a pinhole camera became more common. A pinhole camera was portable, allowing a photographer to take (i.e., draw) pictures that were previously unable to have been copied through the dark chamber or camera obscura. The pinhole camera works the same way as the dark chamber in that a small hole in the side of a desktop-sized box imports an image on the opposite wall. Because light rays travel in straight lines, the image is actually inverted. Mirrors inside the pinhole camera box reflect the image to the top of the box at which point an artist transfers the image onto paper.
Today, with the discovery of film and, currently, digital computers encased in small cases the size of a deck of cards allow multiple pictures to be taken in rapid succession. Photographers can pick and chose the pictures to keep and those to be discarded at the flick of a button.
Engineers have played a large role in the development of cameras from the earliest times — from the chemical solutions used to develop film to the state-of-the-art digitization capabilities of today's modern cameras.
Now, let's create our own pinhole camera just like the pioneers of the 19th century!

Before the Activity

Note: Two weeks before the activity, ask students to bring in a ½ gallon milk or juice carton from home. Ask students to thoroughly rinse the container with warm, soapy water. Remind students periodically to remember to bring in the cartons.
• Gather all necessary materials.
• Cut the top (the side with the pour spout) off each milk/juice carton.

With the Students

Note: at the start of this activity, set out some light sources for students to look at through their cameras. Large flashlights work well, as they are bright and can be appropriately directed.
1. Instruct students to tape a piece of wax paper over the top of the milk/juice carton.
 The pinhole camera hole can easily be poked with a safey pin.copyright
2. Ask them to turn the carton on its side and use a sturdy pin (safetey pin works best) or a small-diameter drill bit/drill to make a very small hole in the bottom of the carton (this would be the outside of the carton, not the inside). (Note: The effect of using different size holes will be a point of discussion later). They should make only one hole that is clean and smooth! Please see Figure 1.
3. When all students have finished, dim the overhead lights in the room and turn on the added light sources.
4. Ask students to look at the light sources through their pinhole cameras. Remind them to look through the waxed paper end. The image they see should be a bit fuzzy, but identifiable.
5. Students can move their cameras closer and farther away from the light sources and see what effect that has on the images.
6. Allow students to experiment with the size of the hole and see how that affects the image. Note: very large holes will not depict an identifiable image; instruct students to slowly increase the size of their pin holes.
7. Gather students together and discuss how their camera worked. See below for discussion ideas. Students may take their cameras home at the end of the day.

Remind students to be careful when using the pins and not to poke each other with them.

To see a clearer image, place a patterned piece of paper, or one with shape cut out, over the light source (i.e., over the flashlight lens).

• Who invented the first camera?
• When where digital cameras first developed?
• How many pictures are developed in America each year?

Pre-Activity Assessment

Key Ideas Review: Discuss key ideas from the lesson again with the students. Do they remember what kind of engineer works with light? (Answer: an optical engineer) How does light travel? (Answer: in straight lines) What was the first camera called? (Answer: a camera obscura) See if any students would like to volunteer to draw a ray diagram on the board.

Activity Embedded Assessment

How Can We Make it Better? Remind students of the importance of iteration in engineering design, and encourage them as they work with their cameras to ask themselves: "How can we make it better?" Encourage students to experiment with new ideas and to be kind and helpful to each other as they share ideas amongst themselves.

Post-Activity Assessment

Class Discussion: Whose pinhole camera worked really well? Why? How does the size of the pinhole affect the brightness of the image on the wax paper? (Answer: The bigger the hole, the brighter the image.) How does the size of the pinhole affect the sharpness of the image? (Answer: The bigger the pinhole, the blurrier the image.)

Students should be encouraged to examine various cameras, inside and out, to see the lenses and how the film is placed to record the images. You may be able to obtain inexpensive old cameras at a local thrift shop, which the students can take apart in class.

For upper grades, find some volunteers to make a much larger camera obscura. In this camera, the camera body should be completely enclosed with a viewport on the side to see the back where the image falls. It's also possible to buy film and place it at the back of this camera to take a long-exposure picture. Details can be found at http://brightbytes.com/cosite/what.html
For lower grades, activities should still be appropriate, although students may require more help in constructing their cameras.

For an additional resource on making and using a pinhole camera, see Kodak's website at http://www.kodak.com/eknec/PageQuerier.jhtml?pq-path=11865&pq-locale=en_US&_requestid=45980

State of Utah, History for Kids, "The Amazing History of Photography," accessed July 31, 2007. http://ilovehistory.utah.gov/index.html

Contributors

Luke Simmons, Frank Burkholder, Abigail Watrous, Janet Yowell, Alison Pienciak