Re: Beams and beaming

[P3D Larry Berlin <lberlin@xxxxxxxxx>]

> Neil Harrington 
>"beamed back to the camera" suggests that such a beam is aimed specifically
>at the camera.  I don't think I've ever had occasion to point my camera at
>anything that did that, and I can't really imagine ever wanting to.

Maybe next time a UFO lands in front of your car you can catch a stereo shot
of some beaming? : -)

>I've always photographed subjects that scattered light in nearly all
>directions rather than beaming it. 

True, and I agree with most of your comments. However, consider that even
though light bouncing off of  a subject is scattered in all directions, it
is only the miniscule portion of it that happens to go in the direction of
the lens that actually gets captured and directed to the film.  That is no
more far-fetched than the concept of sunbeams. They are parallel when
arriving here only because we are 93,000,000 miles away from the source.

I was definitely stretching things to illustrate potential correlation
between the commonly used term and the uncommon device. 

>Whoa, Larry, that's too loose for me!  "Beam" to me implies something much
>more directional than "cone."  You could have a cone with an included angle
>of well over 100 degrees in the case of a wide-angle lens, which is pretty
>hard to see as a beam.  Can we agree that your "cone" is an imaginary
>formation which includes all the beams of light entering the lens?

Cones of light beams are a very frequent occurance in the world of optics.
In holography, a laser beam is spread optically into a cone and then
collimated with other lenses so that the single beam or *all coherent light*
can  evenly illuminate an object, much larger in size than the original
laser beam. Just because it has gone through a lens and become a cone
doesn't remove the descriptive of "beam".

I can agree that in this case the cone is an *imaginary formation*, but that
cone has very little *randomness* by the time it arrives at a small camera
lens. The cone I'm speaking of is actually very directional and as long as
you speak only of those directional beams, collectively as a beam, does the
*imaginary formation* exist. 

And yes, the mirror device, commonly called a beamsplitter, actually creates
two separate light path cones. The word seems to only apply when the extra
device, which is not itself a lens, creates the function of two lenses on a
device that has only one. Certainly no less accurate than *anaglyphic*.

Larry Berlin

Email: lberlin@xxxxxxxxx
http://www.sonic.net/~lberlin/


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