Re: Tesla Coil Photography

In a message dated 99-07-29 06:30:43 EDT, you write:

<< snip
> For the last set of attempted pictures, I used 100 speed film with the 3.5
> aperture.  The exposure was about 5 seconds using the "one Mississippi, two
> Mississippi" timing method with the camera hand held and working the variac
> with the other hand...  I will use the tripod and flex shutter cable next
> time...  One problem was that the film and lens speed (100, 3.5) were not
> great enough for an arc to burn an image on the film with the available RMS
> light from the arc.  Thus, I figure, faster film and perhaps the 1.4 lens
> are needed (I have been reading the archives on this).  If there is enough
> ambient light for the camera electronics to do the exposure, it does a good
> job light wise but the streamers seems dim (with 100 speed film) thus I
> guess the 400 speed would be much better (I have 1000 too).

Hi Terry,

I'm not an expert in photography either, but from my limited experience,
I would tend to agree that you need either a wider aperture, a longer
exposure, or faster film.  I often use a 15 second exposure with ASA 100,
at F2.7 for sparks that are 60" long.  The long esposures will show a
great number of streamers forming a bushy head of sparks.  Shorter
exposures with faster film will show up individual streamers better.  This
might depend on the break rate too to some degree.  It will also depend
on how long the sparks are, and how bright.  I think that for a small coil
giving maybe 15" sparks, a faster film with shorter exposure might give
more dramatic results.  I see a lot of photos of small coils, that show
a great cloud of streamers, which indicates it was a long exposure to
get enough light from the small TC.  A lot depends on the effect you're
looking for too.  You could try a bunch of different exposure times,
F stops, and film speeds, etc, to see what effect you like.  But I'm sure
there are photo experts on the list that will give you exact settings, and
save you all that work, I guess that's the idea anyway.

Different views on gap light too.  Some like to cover or sheild the gap
arc light, others like to let it burn into the photo.  Some add lights aimed
at the secondary to highlight it, etc.  Generally, if you use longer exposures
and/or gap light, and big sparks, you won't need to separately light the
secondary.  I think some even take a normal photo of the coil with the
room lights on, then let the coil run in the dark for the same (double) 

I found that when I took photos of 17" and 36" tube coil sparks, ASA 
1000 was best, with a shorter exposure of about 2 seconds or less, 
otherwise there was just a big fuzz ball of sparks.  

My photos come out reasonably well IMO, but I find photography takes
a lot of patience, and time and effort, thus I do very little of it.  Even
less now than in the past.  It's a lot easier to just swing a camcorder
into position.  But, yes....quality spark still photos, are a joy to see, and
well worth the efforts.  Good for coil analysis too.

John Freau

> Any advice is welcome.  I hate to go through a bunch of sessions and film
> just to START getting reasonable pictures...
> Thanks,
 >  Terry