Single-Lens Experiment

[PK6811S@xxxxxxxxxxxxxx]

As the traffic on photo-3D has evaporated, I deduce that everyone is out
playing with all that new equipment they got for Christmas :-)  So, just
for filler, here is a simple single-lens experiment that YOU CAN DO AT HOME.

Equipment required:

  One large dark room
  One table lamp with shade
  One sheet of white paper
  One simple lens at least 1 inch in diameter (larger is better)
  One piece of opague paper/card about twice the width of the lens

Punch/cut a one-quarter-inch hole at least one lens diameter from the
edges of the card.

Turn on the lamp and place the white paper on the table below it.  Position
the lens between them to focus the bulb on the paper.  With the bulb in
focus, other parts of the lamp will be more-or-less out of focus but
recognizable.  Now hold the card about halfway between the lens and the image.
You can see the 'circle of confusion' that represents the bulb on it.
The image on the paper is darkened but somewhat better focused.

Now move the card around, keeping the cutout within the bright circle which
is the unfocused bulb, and watch the focused image below.  The bulb will
seem to rotate a bit and other lamp parts that are out of focus will move
around.  A larger diameter lens gives a greater effect, however moving
everything across the room from the lamp reduces the effect.

The bulb seems to rotate because each point on the lens 'sees' it from
a different perspective, which is how single-lens 3D works.  The out-
of-focus parts move around because the light rays creating them
have not yet converged or are already diverging, and the cutout
aperture selects only a small portion of them.

Advanced Version Using Red and Blue/Green Filters:

Make another hole in the card close to the original (make up a set
of cards with varying distances between holes).  Place a red filter
over one hole and a blue/green filter over the other one.

Position a two-hole card between the bulb and the sheet of paper.
Taking a pair of red/blue filters in hand, and closing one eye,
look at the image through the red filter.  Then through the blue/green
filter.  Alternate the filters rapidly to see the changes in the image.

--------

Now back to:

   1001 Ways to Suspend Two Cameras on a Bar
   50 Ways to Tell if Your Shutters are in Sync
   Top Ten Explanations of 'What Ortho Means to You'
   Endless Potshots at Camera X (the one the OTHER guy bought)
   Accolades for America's 3D-Viewer Repair Guy (uh.. Mr. T ?)
   
:-)

Paul Kline
pk6811s@xxxxxxxxxxxxxx

Have a Great 1996!

Paul Kline
pk6811s@xxxxxxxxxxxxxx


------------------------------