Re: Colored sparks (photography) (fwd)

---------- Forwarded message ----------
Date: Mon, 15 Dec 1997 11:45:34 GMT
From: Mike Harrison <wwl-at-netcomuk.co.uk>
To: Tesla List <tesla-at-poodle.pupman-dot-com>
Subject: Re: Colored sparks (photography)

On Sun, 14 Dec 1997 22:46:41 -0600, you wrote:

>From: 	Gary Lau  14-Dec-1997 1948[SMTP:lau-at-hdecad.ENET.dec-dot-com]
>Sent: 	Sunday, December 14, 1997 6:35 PM
>To: 	tesla-at-pupman-dot-com
>Subject: 	Re: Colored sparks (photography)
>I shot a roll of film on my coil.  While most of the shots were the
>normal time exposures of the sparks, I was especially anxious to see
>photos of the brilliant yellow sparks I had produced with table salt.
>Upon getting the prints back, the normal shots came out super, but I was
>utterly disappointed in the yellow spark shots.  The arcs were all
>properly exposed, but their color showed absolutely nothing different
>from the normal sparks.  It's like I was photographing ghosts!  How could
>visual and photographic perception be so different?
I suspect the sparks were overexposing, saturating the film - have a
look at the negs - you'll probably find all sparks show as black. 
As sparks are so unpredictable, it's hard to set the correct exposure,
but overexposure of white sparks won't usually look too bad. I'd
suggest doing a sequence of shots with progressively smaller apertures
to get the optimum exposure. Correctly exposed sparks may not look as
dramatic, however, as the overexposure can make them look brighter and
fatter than they really are! 
Slower film might help as well.

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