Spark Photography

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

Original poster: "Ted Rosenberg by way of Terry Fritz <twftesla-at-uswest-dot-net>" <Ted.Rosenberg-at-radioshack-dot-com>

Jason, all:
As a professional photographer and former Manager of Consumer Relations for
Minolta-Ramsey NJ, I'd like to offer the following suggestion for taking
good photos that show off the physical coil and the sparks it produces.

Let me use http://www.flash-dot-net/~ford29/tesla/HHH01.jpg for an example.

I used a Minolta Maxxum which was taken off AUTO and put on full manual.
I mounted the camera on a tripod and framed the coil/dummy.
The ambient light was almost totally dark except for the fluorescent light
from the "Brain in the Aquarium" and a bit of light from the Jacobs Lader.
The film was Fuji ASA 200.
I set the camera to "B" and the aperture to f/8. I pressed the shutter
button and the flash fired, properly illuminating the scene and the coil.
But I kept my finger on the button for another 5-8 seconds. It was during
this time that the sparks and the streames registered correctly.

Naturally, I also bracketed. Film is cheap.
I shot some at f/8, f/11 and f/16. I let the sparks register for 4, 5, 8,
and 10 seconds.

I do not believe the same could have been done with a fancy digital camera
(just my opin) so in this instance...even an ancient Argus C-3 would do the
trick.

Good luck in getting your coil functional once more and in getting those
fantastic photos.

One more thing: consider an acryllic safety shield instead of a conventional
strike ring. Dave McKinon uses it and so do I. A 3/16 or 1/4 thick sheet,
supported as you desire above the primary and at least 1" above it...hole in
the middle for the secondary, of course, disappates strikes easily.
And it looks good and keeps dirt off the primary.

Safety First.

Ted


Subject: Re: Web page and MOT coil


Original poster: "Christopher Telford by way of Terry Fritz
<twftesla-at-uswest-dot-net>" <christophertelford-at-yahoo-dot-com>

Hello Jason Johnson, 

You where saying that you couldn't get any spark
pictures to come out. You might want to try covering
up the flash of your camera with masking tape or
something so that it doesn't wash the sparks out. It
is better if u can get hold of a manuel camera which
allows your to set shutter speed and stuff. I find
that a shutter speed of around 1 second gives good
result, but you should experiment with this to see
what works best. 

Hope this helps, 

Chris Telford
--- Tesla list <tesla-at-pupman-dot-com> wrote:
> Original poster: "Jason Johnson by way of Terry
> Fritz <twftesla-at-uswest-dot-net>"
> <hvjjohnson13-at-hotmail-dot-com>
> 
> Well as promised I've started on my page for the MOT
> coil. The main page is
> pretty bare yet but is at:
>  
>
<http://teslapages.freeservers-dot-com/>http://teslapages.freeservers-dot-com/
>  
> The MOT coil page is coming along nicely but I
> cannot get any pictures of the
> sparks. I tried tonight with my digital camera but
> it works the same as my
> cheap regular camera and the disposable camera I
> tried. The sparks are all
> washed out or the whole picture is just black. I've
> either got to much or to
> little light for the pictures. 
>  
> Also tonight I ran into a problem. After I adjusted
> the spark gap electrodes I
> fired the coil up and seen the reflection of a
> bright orange spark from the
> base of the coil off the snow (I positioned the coil
> so the transformer blocked
> the light from the gap, so I couldn't see anything
> going on down there). I shut
> the coil down and inspected. I believe that it was
> from the MMC to a piece of
> flattened copper tube that connects to the gap. I
> don't know for sure it was a
> LONG way for 4800 volts to jump. I fired it up again
> and had a primary strike.
> I shut it down and readjusted the toroids. I turned
> it back on, the contactor
> pulled in, the variac hummed, but nothing happened.
> I think it has to be my MMC
> but there is no visible damage, and the measured
> value is still within 6% of
> the original, the resistance across the whole cap
> bank is infinite (20 Mohm
> setting, as high as my cheap meter goes) and each
> cap/reseitor checks fine on
> the meter. After I pulled the cap off and measured
> the values I was to cold to
> continue messing with it tonight so I went in the
> house. Ideas besides putting
> it back in and trying it? I'm going to put on a
> strike rail :-)
>  
> Jason Johnson
> 
> 
> 


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