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Re: IT LIVES! "Bizarre" dot explanation

Original poster: "Scott Hanson" <huil888@xxxxxxxxxxxx>

Nir -

It appears you have several different things going on to create "bizarre
dots" in your coil photos.

The first type are round, bright dots of light in a relatively straight or
slightly curved line, usually passing through the geometric center of the
photo. These are caused by internal reflections within the lens of the
camera, each air-to-glass surface creating a reflective surface. To create
these distinct reflections, you need a very high intensity point source of
light. In Tesla coil photos, this is almost always the spark gap. Because of
the different spacing between the surfaces of the lens elements, the dots in
the photo will have different spacing between them. Even in a cheap camera,
most or all of the lens elements will have anti-reflection coatings on all
surfaces, but the light from the spark gap is so intense that reflections
still occur. This phenomenon can also be seen in outdoor photographs at
small lens apertures when the sun is within the field of view.

In other photos, there is a second, identical but dimmer image of a
streamer, offset slightly to the right of the main streamer. This is also
almost certainly the result of internal reflections within the camera lens.

Steve Connor's still-from-video photo is a bit different, with two vertical
columns of bright dots at a perfectly uniform spacing. These dots are
created more complicated mechanism, usually having to do with the pixel
scanning process within the CCD. Note that in Steve's photo, these columns
of dots are directly aligned with the with the spark gap. I think they might
be caused by pixel saturation or memory effects in the CCD. I have also seen
continuously moving, random "snow" dots in video shots that were not aligned
with any optically bright feature in the camera's field of view and that
seem to be caused by electromagnetic interference with the camera's CCD or
CCD scanning process.  These random "snow" dots would greatly diminish or
disappear entirely when the camera was moved a bit further away from the

Scott Hanson
----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Sunday, April 03, 2005 11:41 AM
Subject: IT LIVES!

> Original poster: Nir Weingarten <nirzvi@xxxxxxxxx>

> Hi all

> Please respond on the bizarre phenomenons...

> Thank you all for your great help!

Nir(NOT NEAR) Weingarten