Point, Click, Shoot! Photography with a Pinhole Camera
AbstractDo you like to take pictures with a camera? It can be fun to capture important and humorous events in your life on film or on a memory card. Photography is a hobby that people of all ages enjoy because they can creatively express themselves both artistically and scientifically. But when did the science of photography start and have cameras always been such complicated pieces of equipment? In this photography science project, you will experiment with a simple camera called a pinhole camera and you will determine the correct exposure times for different indoor lighting levels.
Michelle Maranowski, PhD, Science Buddies
To experiment with pinhole photography and determine the correct exposure times for different indoor lighting levels.
Photography is the meeting of art and science. It is an artistic activity because you, as the artist, get to decide what object you want to photograph, where you want to photograph it, and the kind of lighting you want on the object. All of these things evoke a mood and feeling that the artist wants to share with others. Photography is a science because you need to understand how all of the dials and lenses on your camera affect the photograph you snap. For example, what does the f number of a lens mean, what is the difference between a 54-mm lens and a 200-mm lens, and what film speed should be used under certain lighting conditions? The film speed is a measure of how sensitive the film you are using is to light. For instance, if you were taking pictures outdoors on a sunny day, you would use a lower speed of film (which is less sensitive to light) than you would if you were taking pictures indoors or at night.
A camera is an optical device that captures light and exposes film. Since the beginning of photography, camera science has gotten a lot more complicated. But when did photography first start? When did humans first start capturing light and start recording images? According to historical documents, in the 5th century BCE (before common era), the Chinese philosopher Mo Ti was the first person to record the formation of an inverted image (an image in which the top and bottom are reversed) with a pinhole. Mo Ti was aware of the fact that objects reflect light. In the 10th century BCE, Arabian physicist Ibn al-Haythem built the first camera obscura, which means "darkened chamber" in Latin. The camera obscura is a 4-walled dark room with an opening or pinhole in one of the walls. Light enters the hole in the wall and produces an inverted image on the opposite wall. An inverted image is one that is flipped upside-down—the reason why it's flipped is explained in the paragraph below and in this video.
So what is a pinhole camera and how does it actually work? A pinhole camera is a camera with no lens. It is a lightproof box with a very small hole on one side, just like the camera obscura. How does it work? Light reflects off of objects in all directions. If you place a pinhole camera in front of the object, some of the reflected light will enter the pinhole. Because of the direction of the light coming through the pinhole, the image exposed on the film is inverted. Generally, the smaller the pinhole, the sharper, but dimmer, the image will be. Ideally, the size of the pinhole is 1/100th the distance between the pinhole and the screen or film.
Now, what is the difference between a pinhole camera and modern film cameras that some people still use to take pictures? Both the pinhole camera and modern film cameras are essentially lightproof boxes that only allow light in when the shutter or screen is opened. In both cameras, when the shutter or screen is opened, the film is exposed to light. As mentioned above, to get a really sharp image with a pinhole camera, the pinhole should be very small. However, this means that the resulting image will be dim. To improve the image, modern cameras have lenses that focus and concentrate incoming light on the film. Another difference between the pinhole camera and the modern film camera is that the modern film camera has an automated shutter that allows you to precisely control the shutter and, therefore, the amount of time that the film is exposed to light.
Digital cameras also have lenses like the modern film cameras, but the big difference is that instead of light coming into the box and hitting film, the light hits a device that converts it into pixels or electronic information.
In this photography science project, you will build your own pinhole camera from a kit and learn to take pictures with it under different indoor lighting conditions with different speeds of film. This is a science project that will allow you to be both a scientist and an artist.
Terms and Concepts
- f number
- Film speed
- Pinhole photography
- Camera obscura
- Depth of field
- Film negative
- Scatter plot
- How do camera lenses work?
- Why is the image in a pinhole camera inverted?
- In the course of doing your research, from what kind of containers did pinhole photographers make cameras?
- What is the depth of field for a pinhole camera?
The following websites describe the physics and technique behind pinhole photography:
- Wikipedia Contributors. (2009, September 4). Pinhole Camera. Wikipedia. The Free Encyclopedia. Retrieved May 29, 2010.
- Joubert, S., Ed. (2008, April 24). The Pinhole Camera: Low-Tech Photography. Retrieved October 15, 2009.
For help creating graphs, try this website:
- National Center for Education Statistics. (n.d.). Create a Graph. Retrieved June 2, 2009.
Materials and Equipment
- STD-35 Pinhole Camera Kit; available online at www.fatbraintoys.com, item # NO065
- Color film; 6 rolls each of ISO 100, ISO 200, and ISO 400 speed film. Each roll should have 24 exposures.
- Lab notebook
- Table, small enough that you can easily carry it with you (like a small patio table or a card table)
- Tape measure
- Light meter; such as the Light Meter LX1010B,50,000 Lux Luxmeter with lcd display, available at Amazon.com
- Plastic baggies (18)
- Permanent marker
- Graph paper
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Performing the Experiment
Build the pinhole camera using the detailed instructions that come with the kit. Read the kit's enclosed instructions about how to use the camera. Test the camera to make sure that it is working. Load a new roll of film in the camera and take some pictures. The instructions have recommendations on exposure times at certain lighting levels. Follow this guide when performing your test. Once you are done taking pictures on the test roll of film, remove it and take it to your local film developer so that they can develop the film. If the resulting pictures have clear images, then your camera is ready for experimenting. If the film is all white (overexposed) or all dark (underexposed), then you need to go back to the drawing board and fix the camera. You may have to carefully take it apart and redo making it. See Figure 1, below, for an example of an overexposed and underexposed photo.
Figure 1. 1.a. shows a picture that has been overexposed (exposed to too much light) and 1.b. shows a picture that has been underexposed (exposed to too little light).
- You are ready to start the project when you are ready to devote time to using an entire roll of film in one session. You will need to expose the entire roll of film in one day. This will take about 2–3 hours. This means you should take some pictures under one lighting condition, such as a shady room, and then the rest under another different lighting condition, such as a sunny room. Do not take a few pictures and leave the film in the camera for more than a day or your images might become overexposed.
- The instructions that come with the camera are clear about exposure times for ISO 100 and ISO 400 film under cloudy or sunny outdoor lighting conditions; however, in this photography science project, you will extend the instructions included in the kit and add steps for taking pictures indoors. You will take indoor pictures in a shady room in your house or school and in a sunny room in your house or school, both during daylight hours, for ISO 100, ISO 200, and ISO 400 film.
- Following the instructions that came with the camera kit, load a roll of ISO 100 speed film into the pinhole camera. Make sure to use the rubber bands to keep the camera closed.
- Go to a shady room in your house or school. Place the table in the room and put the camera on top of it. Aim the camera at a feature in the room that is not moving or changing (but that you can easily move to another room later), like a poster on the wall or a bowl of fruit. Measure the distance with a tape measure and record it in your lab notebook. Using the light meter, measure the amount of light in the room. Take a light meter reading right in front of the camera so that you get an accurate reading of the available light. Note down the date, the light meter reading, and the time of day in your lab notebook.
- Read the instructions to learn how to advance the film. Decide on the times that you will expose the film at this light level and the number of pictures you plan to take. Use the instructions included in the kit to help you estimate a reasonable exposure time. Once you decide on a starting time (based on the exposure times in the instructions included in the kit), you will systematically increase (or decrease) the length of time that you will expose the film in order to see how this affects the final quality, brightness, and sharpness of the image in the resulting photograph. You can try systematically increasing or decreasing the exposure time by 1 or 2 seconds. Make a data table in your lab notebook to keep track of this information, like the one shown below.
|Picture Number||Roll Number||Location, Date, and Time||Light Meter Reading||Exposure Time|
- Expose the film as you planned in step 6. Use the stopwatch to keep track of the exposure time. Try to take two pictures for each exposure time. You must expose the entire roll.
- Rewind the roll of film from step 7, remove it from the camera, and place it into a plastic baggie. Replace it with another roll of ISO 100 speed film. Write the trial number, the film speed, the roll number, and the lighting conditions on the plastic baggie.
- Move to the sunny room and prepare your equipment. Move the poster or item that you took a picture of in the shady room into the sunny room. Try to place the poster or object the same way in the sunny room as you did in the shady room. Take a light meter reading. Place the table in the room and the camera on top of the table. Place the light meter in front of the camera to record an accurate reading. Record the light meter reading in your lab notebook.
- Write down in your data table the number of images you plan to take, objects you're photographing, and the exposure times. Use the same distance between the camera on the table and the object you are photographing as you did in the shady room. Review the instructions in the kit and estimate a starting exposure time. Again, you will have to systematically change the time that you expose the film in order to see how the exposure time affects the final quality of the photograph.
- Expose the film as you planned in step 10. Use the stopwatch to keep track of the exposure time. Try to take two pictures for each exposure time. You must expose the entire roll.
- Rewind the roll of film, remove it from the camera, and place it into a plastic baggie. Write the trial number, the film speed, and the lighting conditions on the plastic baggie.
- Repeat steps 4–12 using ISO 200 speed film. You might have to wait for another day so that you can expose the film at exactly the same time and with the same lighting conditions at which you exposed the 100-speed film. Think about the exposure times that you plan to use. Should they be longer than the exposure times you used for the ISO 100 film or shorter? Record the exposure times and locations in another data table in your lab notebook.
- Repeat steps 4–12 using ISO 400 speed film. You might have to wait for another day so that you can expose the film at exactly the same time and with the same lighting conditions at which you exposed the 100 speed film. Think about the exposure times that you plan to use. Should they be longer than the exposure times you used for the ISO 100 film or shorter? Record the exposure times and locations in another data table in your lab notebook.
- Now take the rolls of film to get developed. Be sure to include the information from your data tables on the film envelopes so when you get them back you know which is which. After developing, you will receive both the film negatives and the photographs. Review your photographs. How do the photographs look? Can you see a difference between the exposure times at each lighting level and how the different ISO speed films reacted with the light?
If you are happy with how your photographs look, repeat steps 4–15 two more times. Whenever you do a science experiment, it is important to repeat your experiment at least three times to make sure that the data (in this case, photographs) you gather is accurate and reproducible.
- If you are not happy with your photographs, then repeat steps 4–15 using different exposure times. If you are not happy with just one set of exposures, then just repeat that part over again.
Analyzing Your Data
- Find the best (clearest and sharpest) picture for each trial, film speed, and lighting level. Average the exposure times of the pictures for each lighting level and film speed over the three trials. Record the average exposure time for each film speed and lighting level in your lab notebook.
- Plot the average exposure times on a graph. You can make the graphs by hand or use a website such as Create a Graph. Label the x-axis Film Speed and the y-axis Exposure Time. You can plot the data for the different lighting levels on the same graph.
- Now look at all of the pictures that you took for each speed of film. Separate the pictures by exposure time. Give each picture a number and then determine how overexposed or underexposed each image is on a scale of 1 to 5, where 1 is completely underexposed and 5 is completely overexposed. Remember, objects in a picture that is underexposed will look darker than they actually were. Objects in a picture that is overexposed will look too bright. There is also a loss of details in overexposed pictures. Record your data in a table like the one shown below.
|Trial||Film Speed||Picture Number||Lighting Level||Scale of Exposure||Exposure Time|
- Now plot the data from this data table on a scatter plot. You can plot the data by hand or use Create A Graph, mentioned in step 2 of this section. The scatter plot is a sub–type under the XY graphs. Label the x-axis Exposure Time and the y-axis Scale of Exposure for each film speed and lighting level.
Ask an Expert
- Can you make a pinhole camera from a different container? There are many instructions online detailing different ways of making a pinhole camera. Try one of them out and compare the resulting photographs with the photographs you took with the camera from the kit. Do the exposure times change?
- Try night photography with your pinhole camera. Use ISO 400 film and set long exposure times. Does it work? If not, you may have to get special high-speed film.
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