P3D Re: Floating 3d from down-the-earth?

[roberts@xxxxxxxxxxxxxxxxx (John W Roberts)]

>Date: Tue, 23 Dec 1997 07:16:57 -0700
>From: fj834@xxxxxxxxxxxxxxxxxxxxx (Dr. George A. Themelis)
>Subject: P3D Floating 3d from down-the-earth?

>So, is there a mechanical way to lift the camera higher and how high would
>that be?  Tripods are limited to 6 feet or so.  Same for monopods.  I have
>been tempted to join two monopods to get to 12 feet.  I would guess that
>someone must have gone through the same train of thought an constructed a 
>long collapsible monopod to get you to 20 feet or so.  Is there any
>information around?  The stereo system can be something as simple as a
>Stereo Realist (for those who don't mind the limited depth range) or a twin
>camera rig.  Camera(s) can be fired with air bubble release cables.  Seeing
>what is photographed is certainly a problem that that's also the case with
>rockets, etc.

>Any ideas for this more down-to-earth project?

As in all such cases (3D photographers confronted with a significant mechanical
problem not involving the internal workings of a camera), I would strongly
recommend that the first step be hanging out with radio amateurs, attending
hamfests, and so on. The radio folks have been handling this type of situation
for at least the last 50-60 years.

For a tall, rigid structure, three parallel elements (the points of 
intersection with a plane perpendicular to the orientation of the elements
forming the vertices of an equilateral triangle), these elements being
cris-crossed with support elements also defining triangles, is one common
way to achieve strength and light weight. Circular hollow tubes also have
great strength to weight ratio. Circular tubes and triangles are often
combined in compound structures. For a mast of a fixed height, guy wires are
often used for additional support.

I have seen collapsible antenna poles, which can be transported to a chosen
location and extended to a considerable height.

The Handbook for Radio Engineers probably has a lot of this information,
as well as formulas for calculation of wind forces on an antenna structure.

To see what you're photographing, why not put a video camera near the 3D
camera, with a cable running to the ground, and a monitor?

John R (not a radio amateur, but attender of hamfests)
[currently on vacation]


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