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Re: [Phys-l] pinhole camera



What you see on the screen is a superposition created by assuming the source is an ensemble of point sources, each of which creates a point source on the screen. The superposition gives the total image. So to me the image is neither real nor virtual since those of words that describe images formed in a different way.

joe

Joseph J. Bellina, Jr. Ph.D.
Professor of Physics
Saint Mary's College
Notre Dame, IN 46556

On Apr 12, 2007, at 3:54 PM, Michael Porter wrote:

On 4/12/07, Anthony Lapinski <Anthony_Lapinski@pds.org> wrote:
...
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).

Could you make the argument that what is formed by a pinhole camera
isn't really an image (real or not)? There is no coherent
recombination of light rays in a pinhole camera, just divergence. What
appears on the screen is more like a complicated shadow than an image
in terms of how it is formed.

With an actual real image formed by a lens, you can remove the screen
and still see the image if your eye is lined up with the object and
the lens. You cannot do this with a pinhole camera.

Sorry that doesn't help you with your query (others have already
helped there... I'm hungry for oatmeal cookies now!).
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