Seeing is Believing
(Making a Pin-Hole
Camera)
Grade 7 Activity Plan
1
Seeing is Believing (Pinhole Camera)
Objectives:
1. To demonstrate that light needs to be reflected off of particles in order for us to
see it
2. To show that light travels in straight lines and in all directions
3. To demonstrate that images are projected upside-down onto our retinas
4. To understand the essential components of a pinhole camera
5. To know how to take a good pinhole camera picture, and to be familiar with the
chemical processes involved in film development
Keywords/concepts: light, photon, pinhole camera, lens, aperture, diaphragm, film,
silver halide crystal, developer, stop solution, fixer, negative, pixel
Take-home product: pinhole camera picture
2
Segment
African Proverb
and Cultural
Relevance
(2 min.)
Details
“When the moon is not full the stars shine more brightly.”
Buganda, Uganda.
Pre-test
(2 min.)
What is essential to sight?
Introduce light and how important it is to sight. Ensure everyone
understands the concept of a photon, and the speed at which
light travels.
Demo 1: How is
light seen?
(3 min.)
Using a laser pointer and chalk dust, demonstrate how light is
seen and the path it travels.
Demo 2: How does
light travel?
(5 min.)
Cover a lamp with black construction paper, and make various
pinholes to observe the manner in which light travels
Demo 3: How is
light reflected?
(5 min.)
Using a garbage bag and can, demonstrate how images are
reflected upside down onto our retinas
Pinhole Camera
(10 min.)
Introduce the pinhole camera, and compare it to the human
eye, lens cameras and digital cameras. Ensure students
understand the film developing process and the underlying
chemistry at each stage.
Activity 1
(10 min.)
Using the properties of light demonstrated in the prior activities,
create a pinhole camera that will be used to take pictures. If
cameras are pre-made, simply explain how to make one.
Activity 2
(50 min.)
Go outside so there is ample light, and have each student take
their own picture. Take each student into the dark room to
develop their picture.
Post-test
(5 min.)
Lead students in completion of a Cross-word Puzzle
Suggested interpretation of the proverb: When something goes wrong, pick up the
slack. In today’s experiment, things might not go as planned; we might not get a good
picture the first time we try. But if something goes wrong, everyone should work their
hardest to be a star, pick up the slack, and get it right the next time.
3
BACKGROUND INFORMATION
Light is nature's way of transferring energy through space. Light travels very rapidly, but
it does have a finite velocity. In a vacuum, the speed of light is 186,282 miles per second
(or nearly 300,000 kilometers per second). Physics experiments over the past hundred
years or so have demonstrated that light has a dual nature. In many instances, it is
convenient to represent light as a "particle" phenomenon, thinking of light as discrete
"packets" of energy that we call photons. The other way of representing light is as a
wave phenomenon. An analogy is sound waves. High pitched notes have shorter
wavelengths, or distances between each successive wave. Likewise, blue light and red
light are both just light, but the blue light has a higher frequency of vibration (or a
shorter wavelength) than the red light.
A pinhole camera is the simplest camera possible. It consists of a light-proof box, some
sort of film and a pinhole. The pinhole is simply an extremely small hole like you would
make with the tip of a pin in a piece of thick aluminum foil. A pinhole camera works on
a simple principle. Imagine you are inside a large, dark, room-sized box containing a
pinhole. Imagine that outside the room is a friend with a flashlight, and he is shining the
flashlight at different angles through the pinhole. When you look at the wall opposite
the pinhole, what you will see is a small dot created by the flashlight's beam shining
through the pinhole. The small dot will move as your friend moves his flashlight. The
smaller the pinhole (within limits), the smaller and sharper the point of light that the
flashlight creates.
Now imagine that you take your large, dark, pinhole-equipped room outside and you
point it at a nice landscape scene. When you look at the wall opposite the pinhole,
what you will see is an inverted and reversed image of the scene outside. Each point in
the scene emits light, and, just like the flashlight, the beam of light from that point
passes through the pinhole and creates a point of light on the back wall. All of the
points in the scene do that at the same time, so an entire image, in focus, is created on
the back wall of the room. The image is very dim because the pinhole is so small, but
you can see it if the room is very dark. A pinhole camera is simply a smaller version of
that room, and the film inside the camera replaces you. The film records the image that
comes in through the pinhole. The pinhole in a pinhole camera acts as the lens. The
pinhole forces every point emitting light in the scene to form a small point on the film, so
the image is crisp.
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Demo 1: How is light seen?
Purpose: To demonstrate that light needs to be reflected off of particles in order for us to see it
Item
Laser Pointer
Chalkboard Eraser
Quantity (for mentor)
1
1
Procedure:
1. Shine a laser at a wall. Show students how they can see where the light begins at
the source and where it ends on the wall, but not the path the light travels.
2. Demonstrate how to show the path of the laser by getting a student to clap two
chalk board erasers together to make a dust cloud around the laser beam. The
path of light now becomes visible. Why?
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Demo 2: How does light travel?
Purpose: To show that light travels in straight lines and in all directions
Item
Lamp with shade
Quantity (for mentor)
1
Black Construction Paper
Pin
1
1
Procedure:
1. Draw both a curvy and straight line on the board, and ask students to choose
the one that is the shortest.
2. Cover lamp shade with black construction paper.
3. To demonstrate that light travels in a straight line, poke holes in the construction
paper with a pin. Darken the room and look at how light shines through the
pinholes.
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Demo 3: How is light reflected?
Purpose: To demonstrate that images are projected upside-down onto our retinas
Suggested format: Mentor demonstrates first, and then invites students to come try for themselves
Item
Black garbage bag attached to can
Quantity (for mentor)
1
Procedure:
1. Hold the can in one hand about a foot away from your face, so that the flat
screen is facing you, and the hole is pointed towards a light source (a window
works well).
2. Turn off the lights.
3. Place the garbage bag over your head to block other light sources, and observe
the image that appears on the screen.
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Activity 1: Making a Pinhole Camera
Purpose: To understand the essential components of a pinhole camera
Suggested format: Complete this activity before going to the school, so each student has time to take and
develop his/her own picture. Be sure to explain to the students how to make a pinhole camera should they
want to experiment at home. Below are instructions to make ONE camera from scratch.
Item
Small cardboard gift box
Black electrical tape
Sheets of thin cardboard
Aluminium foil
Thumb tack
Scissors
Black Paint*
Ruler
*contingent on the type of box found
Quantity (for one camera)
1 box
1 roll
2
1 roll
1 small pack
1
500mL
1
Procedure:
1)
2)
3)
4)
Find small cardboard boxes with removable lids.
If the box is not black on the inside, you may want to paint the inside black*
Tape all corners and edges with black electrical tape to make the box light tight
On one side of the box, cut a hole the size of your thumb (it does not have to be
perfectly circular). This will be where the pinhole is placed.
5) Cut a square piece of aluminium foil large enough to fit over the hole. Make sure
there are few to no wrinkles in it.
6) In order to make the pinhole, place the aluminium foil on top of a soft material
(e.g. a small stack of napkins, or thick cardboard). Hold a thumb tack between
your thumb and forefinger and roll it from side to side to slowly pierce a pinhole
in the aluminium foil.
Note: Do not simply push the thumbtack through the foil. This will produce a hole that is not
round!
7) Tape the aluminium foil with the pinhole on the inside of the box to cover the
larger hole.
8) Cut sheets of thin cardboard to make four narrow panels no longer than the
height of your box. Tape two of them onto the back wall of your box to hold the
film in place.
9) Tape the other two panels to the outside of your box, at the front, on either side
of the pinhole. Leave enough space for a thin sheet of cardboard to slide in and
out of place to serve as a shutter.
10) IN THE DARKROOM, cut sheets of film to the correct dimensions in order to slide
into place on the back wall of your box. Cut one sheet of film for every student
plus a couple extra, and place them back in the bag to be used later.
Additional Resources:
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Video - How to make and use a pinhole cam: http://www.youtube.com/watch?v=KmJznKe4jpI
Written instructions: http://cdn.makezine.com/make/wp_pinhole.pdf
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Activity 2: Taking and Developing your picture
Purpose: To know how to take a good picture, and to be familiar with the chemical processes involved in
film development
Suggested format: Students will take pictures in groups of two
Item
Pinhole Camera
Squares of film cut to size
Developing Solution
Stop Solution
Fixing Solution
Water
Red Light Lamp
Plastic Trays
Gloves
Quantity (10 students)
5
10
335mL
150mL
750mL
250 mL
1
4
11 pairs
Procedure:
1) Cut (if you have not already done so) and load film in the dark room. Make sure
the box is light tight before turning on the lights
2) Go outside, and place the box on a steady surface. Open the shutter, and let
the box sit still for 1-2 minutes (this will depend on the exposure time of the
camera on that day). Make sure anyone in the picture remains still.
3) Close the shutter, and carefully take the camera to the dark room.
4) Put on gloves.
5) In the dark room, lay out three containers, and pour in developer, stop solution,
and fixer (just enough to submerge the film). Lay out the fourth container in a sink
and turn on the tap to create a water bath.
6) Turn lights off, and turn on red light lamp.
7) Take the film out of the camera, and place it in the developer solution until you
see an image start to appear. You can control for overexposure by removing the
picture quickly if it starts to get too dark.
8) Transfer the picture to the stop solution.
9) Transfer the picture to the fixer and swish it around gently.
10) Place the picture under the running water for a few seconds and gently wave it
through the air until it dries.
Additional Resources:
Image and explanation of the photochemistry of silver salts:
http://www.cheresources.com/content/articles/other-topics/chemistry-of-photography
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The Pinhole Camera
1
2
3
4
5
6
7
8
ACROSS
2 The light sensitive material on which the
image is developed
5 Light travels in a ________ line
6 In the picture developing process, it
converts silver ions to silver metal
7 In the picture developing process, it
neutralizes the developer solution
8 Light energy is contained in bundles
called _______
DOWN
1 The simplest type of camera
3 In the picture developing process, it
rinses off remaining chemicals on film
4 Pupil is to the human eye as ______ is to
the pinhole camera
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