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Exposing for Lightning at Night
By Jim Zuckerman
Lightning is one of those subjects that cannot be accurately measured by a light meter. If you are attempting to capture daytime lightning, you can read the ambient light with either a reflected meter or spot meter. A separate exposure calculation for the lightning itself need not be made. The white tentacles of the lightning will register as white on the film in the properly exposed sky. There is no details in the bolts that can be gained or lost due to an exposure variance.
When lightning strikes at night, however, both reflected and incident meters are useless. The only way to determine a proper exposure is with experience and some good old-fashioned trial and error.
With Fujichrome Velvia, which I rate at EI 40 (despite its ISO rating of 50), here is how I expose for lightning at night: First, I drive to a remote location away from city lights to avoid as much ambient light as possible. Then I mount my camera on a sturdy tripod and lock the shutter open with a locking cable release. Pointing the lens in the direction of the anticipated lightning bolts, I leave the shutter open for a minute or two, while waiting for one or more lightning strikes.
If the shutter remains open for longer periods, the low level of ambient light will eventually fog the film and reduce the contrast of the shot. However, if I’m in the desert on a moonless night, I may leave the shutter open for as long as 10 minutes.
I set the lens aperture at f/4 when shooting distant lightning that is at least several miles away. With bolts that are only a mile or two in the distance, I use f/4.5 or f/5.6. If the lightning is very close – or even above my head – I use f/8 or f/11 (although the smartest thing to do under these circumstances might be to take cover).
It is not necessary to use faster film unless you prefer to do so. No filters are required, although lightning often photographs with a magenta cast. If you find this objectionable, a green filter will neutralize the color. If you prefer lightning skies with a blue cast, try shooting with a tungsten-balanced film like Fujichrome 64T.
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