Re: Sparks - Bright in the middle, how to verify it -suggestion

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-uswest-dot-net>" <jimlux-at-earthlink-dot-net>

Actually, a very special electronic flash (the typical xenon unit isn't fast
enough), using a very short arc in air or hydrogen or argon.   You need a
flash duration of a microsecond or so to get good bullet photos.  (The
standard GR strobotac can make flashes that short BTW)

But, what you want for details of the spark growth is something like a
streak camera.  The pros studying this sort of thing use image intensifiers
that have scanning deflection plates.

But, before going to the trouble of trying to get nanosecond exposure times,
I'd start with the 1/10,000 kinds of exposures with a video camera and see
what it looks like.

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Tuesday, January 23, 2001 6:04 PM
Subject: Re: Sparks - Bright in the middle, how to verify it -suggestion


> Original poster: "bob golding by way of Terry Fritz <twftesla-at-uswest-dot-net>"
<yubba-at-clara-dot-net>
>
> Hi Chuck all,
>     I think those pictures of bullets and humming bird wings all relied on
> the short duration of an electronic
> flash. I agree with Mike H that the problem will be getting enough light
> without killing the contrast and losing
> the spark in the light. I have seen film of arc formation in arc welding
> taken at high speed. This was done at the
> welding institute here in Cambridge. Could be worth asking them how they
> did it. I think they may have changed
> there name by now. It could work with a single shot well controlled coil,
> the problem will be to not fry the
> camera. I will try my digital camera set on Bulb setting with as little
> light as possible and see what happens.
>
> cheers
> bob golding
>
> Tesla list wrote:
>
> > Original poster: "Charles Hobson by way of Terry Fritz
> <twftesla-at-uswest-dot-net>" <charles.a.hobson-at-btinternet-dot-com>
> >
> > Hi Matt and all
> >
> > What you saw precisely describes the sparks  I saw at low power.  I
would be
> > interested in any photography of them. There have been many  most
> > interesting responses to the question of sparks being bright in the
middle.
> > I think that high speed photography techniques might provide some
answers.
> > Back in about 1959 or 60 I went to a symposium on Photography and Lenses
in
> > Los Angeles and saw some fascinating motion pictures of bullets and
other
> > high speed projectiles. They were astonishing to say the least. (I did
> > manage a hand shake with Wernher von Braun who was there at the time.)
The
> > photo technology is there to take the pictures. The  only problem is
> > getting funding to do it as one of the responses to this phenomena
> > indicated.
> >
> > Cheers   Chuck
>
>
>
>