Lightning is one of the most powerful and spectacular forces of nature. Sudden bright streaks of light split the sky in unpredictable patterns. This unpredictability and speed is probably part of what attracts photographers to lightning. Its the challenge of capturing something so fleeting that makes it really interesting.
While it may seem like lightning photography would be nearly impossible, it is acutally relatively simple when using a slow shutter speed.
1. Set your camera to manual
Set your camera to manual exposure and focus in order to improve your chances at a successful lightning photograph. Just like fireworks photography, lightning photography is about holding the shutter open and waiting for the light. Set your film speed to 100 and your aperture to around f8. Start with a 15 second exposure
2. Use a tripod
Using a tripod or other sturdy base allows your camera to remain still for the extended exposures needed for lightning photography.
3. Pick a storm and location
Picking the "right" storm is one of the most important parts of lightning photography. A storm with frequent lightning is preferred over one with very little lightning. Also, a slow storm will give you more opportunities to capture the image you want than one moving quickly. Finally, a storm at dusk or night will make it easier to get proper exposure than daytime storms.
Pick a location that is safe. Remember that lightning is extrememly dangerous and potentially deadly. According to the National Weather Service, NO outdoor location is safe if you can see lightning or hear thunder. A sturdy building or a car is a safer. You don't need to be in the storm so shooting through a window should not be a problem from rain.
4. Set your exposure/focus
There is no "perfect" setting for lightning photography. Like fireworks photography, the exact settings will vary depending on the intensity and amount of lightning. However, you can pick a relatively safe starting point and adjust your settings as needed from there.
To start set your camera at infinity focus, 100 ISO, F16, and shutter speed of 20 seconds. Remember that your camera battery lasts a long time at microtime exposures but long exposures will run down a battery quickly.