Re: [Phys-l] pinhole camera

["Marc \"Zeke\" Kossover" <zeke_kossover@yahoo.com>]

I cannot over recommend Bob Miller's Light Walk found on the Exploratorium's website. Even if you already understand pinholes and images perfectly, it is worth reading and seeing his pictures because it will help you understand how to explain these ideas. His thinking is very powerful. The first page is here http://www.exploratorium.edu/light_walk/lw_page_1.html 
 
The rest of the work can be found here. http://www.exploratorium.edu/light_walk/. It gives an amazing introduction to pinholes and lens with things that you have around school and things that students have at home. 
 
Marc "Zeke" Kossover

----- Original Message ----
From: Joseph Bellina <jbellina@saintmarys.edu>
To: Forum for Physics Educators <phys-l@carnot.physics.buffalo.edu>
Sent: Thursday, April 12, 2007 1:02:08 PM
Subject: 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!).
> _______________________________________________
> Forum for Physics Educators
> Phys-l@carnot.physics.buffalo.edu
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