Re: [Phys-l] pinhole camera

[Gary Karshner <gkarshner@stmarytx.edu>]

Anthony,
        I have a demonstration I have used using a clear light bulb, a 
lens, a piece of foil and a ground glass. All mounted on an optical 
bench.  The initial setup is with the foil removed to focus the lamp 
filament on the ground glass using the lens. The bench I use allow the lens 
to be folded off  to the side. Next place the foil in a frame that mounts 
it just in front of where the lens was. Using a pin, punch holes in a foil, 
you will see a series of images of the filament on the ground glass. One 
for each hole. Now return the lens to its up right position. You will get a 
single image of the filament. It illustrates how a lens image can be 
composed of a series of rays, as well the operation of a pinhole camera.
        I hope this helps.
Gary

At 01:27 PM 4/12/2007 -0400, you wrote:
> When I teach optics in my (high school) course, I traditionally discuss
> reflection leading into plane and curved mirrors, then refraction leading
> into lenses. Does anyone incorporate pinhole cameras when they teach this
> topic? It has been in the back of my mind for years, but there is
> little/no math involved and "higher level" textbooks rarely mention them.
>
> I am thinking it would be a good way to show students that light travels
> in straight lines, and to introduce them to real images (rather than begin
> with virtual images in a plane mirror).
>
> Does anyone have a class activity/demo/lab (or a useful web site) they
> could share so I can get some ideas about how to introduce/use this simple
> device (e.g., made with paper towel roll and foil)  and have student begin
> to understand how images are formed? A lab activity with questions is what
> I'm looking for. Thanks!
>
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