Re: Tesla Coil Photography
>Apparently, if the room is dark, the exposure time only determines how many
>streamers are captured. The film speed and aperture really determine how
>bright the sparks are in the photo. Thus, you can get a few streamers or
>many depending on how long the exposure is. I never realized this
It's a combination of aperature AND shutter speed that determine the amount
of light let in. For a nonmoving subject, there is little difference between
a slow shutter speed with small aperature, and a fast shutter speed with a
larger aperature. The main difference is that with a wide aperature, your
depth of focus is more narrow; that is, things in front of and behind the
subject are less focused. With a smaller aperature and slower shutter speed,
much more of the foreground and background are in focus.
Of course, with a moving subject, the longer the shutter is open, the more
sparks you will capture. If you've ever seen pictures of waterfalls where
the water looks blurry and kinda misty, they used a longer shutter speed. I
would assume the same would be true of sparks; if the shutter were left open
too long, you'd just have a big purple blur.
If the room is dark enough, you soon hit a point where the aperature won't
open any more, so you then either have to slow down the shutter speed, or
use a different film. I've captured comets with ASA 400 film. You can try
1000 film, but be aware that the photo will be grainier than with a 400.
Probably no big deal, unless you want large prints.
I'd be glad to answer any off-topic photography questions you may have at:
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