Inexpensive and Simple Pinhole CameraDouglas John Weiss, Department of Physics, SUNY-Buffalo State College, 1300 Elmwood Ave, Buffalo, NY [email protected] pinhole camera is a useful tool for teaching optics. They can be constructed in many different ways, depending on the purpose. This is one easy way to make a simple, cost-efficient pinhole camera that is useful for the physics classroom and a good fit for your physics department budget.AcknowledgementsThis manuscript fulfills PHY 690 requirements as part of the Physics Education Masters program at SUNY-Buffalo State College, guided by Dan MacIsaac.IntroductionPinhole photography and pinhole cameras are relatively inexpensive and easy to construct. There is a movement in the artistic community that utilizes this photography format for its unique range of depth and artistic control and freedom that this camera typeprovides. Even digital pinhole cameras are becoming an artistic craze4, 10, although, an understanding of the principles of photography requires an understanding of classic analog photography. Digital cameras make automatic much of what a photographer once had to do on their own. Pinhole cameras are equally attractive to physics teachers who favor a demonstration and model based approach their lessons. Both in physics education and the artistic community pinhole photography has maintained a core underground following, and is starting to surge in popularity4, 10. Pinhole cameras have relevant physics applications, in particular optics. Many of the principles within optics that are usually demonstrated with diagrams, can be illustrated in a hands-on manner through pinhole photography8, 2. Pinhole cameras are especially powerful as an introductory tool exploring the physics behind lenses and mirrors. The format through which this occurs can vary from inquiry based to an interactive laboratory demonstration format. The mathematics of the pinhole cameras is a fairly easy quantitative experience for high school physics students. Simple concepts suchas light travels in straight lines, and including the more complex topics (diffraction) can be demonstrated using the camera. Pinhole cameras provide a hands-on experience for students and sets up more than one opportunity for students to predict, test and discuss physics concepts. The use of pinhole cameras in the classroom provides an avenue for discourse that is valuable in engaging more students in the class.PurposeThe purpose of this project is to find a cheap and easy way to build such a camera with the focus on its relevance to physics being the primary function. Artistic images and functionality are secondary considerations. This camera design is made to have the functionality and price range of a physics-teaching tool. For this reason material selectionwill have a first priority of cost effectiveness while meeting minimum picture quality standards. It is also important to keep in mind, especially when selecting a container for the camera body, that the materials must be easy to obtain in moderate quantities, as the cameras will be a similar size and provide comparable results. Physics of the Pinhole CameraPinhole photography is a standard application of many concepts within physics and specifically optics. Concepts such as light travels in straight lines to aperture interference can be illustrated. There is also physics involved in the set up and construction of the actual pinhole camera. There are several dimensions that can be varied for different effects and images. Focal Length and Aperture10,11,12The dimensions of both of these aspects of the camera are directly related to each other. There are variations of this equation, for this reason I will initiate consensus and use the forms of the equations that I have come across most frequently.The size of the aperture based on a desired focal length can be found by the following equation11:Diameter = (4 * focal length * wavelength of light)^.5* Be sure to convert focal length and wavelength of light dimensions to millimeters when calculating aperture diameter. The average wavelength of visible light is 0.00056 mm.General StructurePinhole cameras are simple in their make up. There is only a need for several decisions to be made that affect the dimensions of your camera. The basic structure components are a box, a hole that allows light to enter the camera, and that medium for capturing the image. The medium for capturing an image is a significant part of the cost of a pinhole camera. This is, of course, a reoccurring cost and therefore careful consideration needs to be given to select the best combination of cost with product functionality and ease of use.For both cost, and ease of use, film paper seems to be the best fit. It is easily the cheapest route to go for film. Film paper comes in individual sheets that each captures one image. There is no additional preparation needed. Also, because each sheet is separate there is nowaste due to accidental exposure that could occur with a roll-film type of media. Ilford seems to be one of a very few brands in this shrinking product field.The body of the camera will be made of cardboard from commercial packaging toensure low cost and consistent dimensions. The body of the camera determines the focal length of your pinhole camera. Since we are using boxes that already exist at a particular size and therefore, focal length, we can use the aperture diameter we have calculated. Proposed Materials and ConstructionThe BodyIn the interest of keeping this pinhole camera in the range of a classroom budget cardboard is the best choice for its combined availability, cheap cost, and flexibility. The body of the camera, no matter what the dimensions, or shape of the film plate can be fashioned from cardboard9. There are a variety of routes to go when gathering supplies for camera construction. Many commercial packages offer all the material that would be needed for the bulk of the camera. If your interest is in creating many uniform cameras for groups within a class, commercial product packaging provides uniform dimensions and/ or rigidity. The body of this camera will be made from an empty paper ream box. The cost practicality here is significant. Every school uses paper, most quickly, making it a short time to stockpile enough of these empty boxes. The dimensions of this box are usually 43.5 cm by 29 cm, with a depth of 25 cm. taking the longer side of the box to
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