Kent,

Five resources that might be helpful:

1.  pinholevisions.org -- simple inventions, simple
language, lots of quick information.

2.  optics.org -- professional organization for
everything optics, including shopping for materials.

3.  sonicarchitecture.com -- designers who create
environments based on sound.  Sure, it's not optics,
but their environments might give you some good design
ideas.

4.  Egg -- PBS arts show.  There was an episode they
aired within the last year featuring a guy who makes
pinhole cameras out of everything, including oversized
plexiglass animal models.

5.  inventors.about.com -- "Biographies" of famous
inventions.  Good historical and technical info.  The
specific page for telescopes on this site is

http://inventors.about.com/gi/dynamic/offsite.htm?site=http://www%2Disds.jpl.nasa.gov/cwo/cwo%5F54ga/html/cd/telescop.htm



I also have some Questions and suggestions:

1.  The "camera" will be able to focus on both the
distant skyline and people in close range?  Does that
mean the can be manipulated for directing and focusing
purposes?  If so, I think crank operations might be a
good idea.

2.  The image will be projected on the "back of a
frosted or translucent imaging glass?"  If you mean
"through" the glass so that it actually projects on
the opposite side, then I think your problem of not
being able to enclose the space could be solved.  I
know it sounds silly, but check out the Kenneth Cole
store on 57th and Lexington in the city.  They have
excellent examples of glass that offers transparent
projections.  The sales reps couldn't tell me the name
of the material, though.

3.  You want the kiosk to provide an experience with
the human eye, the camera eye, and the mechanics of
lenses?  I have some ideas for the human eye portion.
I'd rather discuss them off-line, though, if you're
interested.

Jerry's suggestion about using mirrors is a valuable
one.  Not only will the use of mirrors enable you to
flip the image and save some space, but it will also
enable you to direct the image anywhere you want it to
go.  It might even be interesting to make part of this
kiosk an activity where a visitor can control a mirror
and observe outcomes.  Also, I wonder if two mirrors
mitered at an angle could send the image in two
simultaneous directions without losing the image's
quality.  That could really expand the kiosk's
opportunities.

Good luck with everything.  Sounds like a really cool
exhibit.

Dan

--- Keepsafe Systems/Jerry Shiner <[log in to unmask]>
wrote:
> At 03:57 PM 24/10/01 -0400, you wrote:
> >I'm looking at projecting an image of the skyline
> across the distance of
> >3 to 6 feet within a tube (oversized camera lens) I
> would like to keep
> >this focal length small to keep the housing small
> but would also like
> >an image of about 12 to 18 inches in diameter.
> Ideally, this lens
> >configuration would allow a depth of field to
> accommodate focus on
> >the skyline and on people in front of the 'camera'.
>
> Kent,
>
> You're setting yourself quite a problem here, as you
> are combining opposites:
> a longer focal length (usually in mm or inches, but
> yours is in feet)
> essentially means more magnification and less (much
> less) depth of field
> you'll need a very large lens to make the image
> bright enough. Again you
> will have problems with depth of field (very large
> diameter to focal length
> = wide "f stop" = minimum depth of field)
>
> You might consider something done with one or more
> mirrors. This would
> allow you to reverse the image, and also to set the
> lens above people
> height. Everything would be distant, so no depth of
> field worries. The
> magic of a real image projected on a ground glass
> (get a good one) will
> compensate for many other sins. Beside's a large
> lens at ground level would
> be putting a substantial investment in harms way.
> The mirrors would
> elongate the path for a telephoto effect without
> taking up valuable floor
> space. The ground glass screen could be positioned
> and angled for maximum
> visibility and in the darkest possible area (very
> important), and again,
> out of harm's way.
>
> a full scale mock up means a proper lens. Why not
> make a working smaller
> scale mock up? The effect on the viewer will be the
> same.
>
> You might find an amateur telescope maker to grind a
> lens for you. You
> don't need a camera's or good telescope's compound
> lens system for
> chromatic correction, just a simple single convex
> lens would do. Please let
> me know (off line) what you decide to do, and
> contact me off line if I can
> be of any help dreaming this.
>
> js
> [log in to unmask]
>
> Jerry Shiner
> Keepsafe Systems
> Microclimate and Oxygen-free storage supplies and
> solutions
> www.keepsafe.ca
> toll-free 800 683-4696  fax: (416) 703-5991
>
>
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