But keep in mind that lightning shots just like sunsets are not that impressive on their own. This is why it helps to have a foreground that can complement your lightning filled sky. In essence our lightning filled sky becomes our impressive backdrop for a foreground that will be more of an anchor point to help give our image depth and a touch of uniqueness. The moment we select a foreground subject, which in most cases will be artificially lit, our overall exposure for the lightning will be limited by the exposure needed for the foreground subject (unless it’s not lit, and will be used as a silhouette). The exposure for the foreground subject doesn’t need to be exact since it usually takes up a small part of the frame and is usually of secondary importance compared to the lightning shot.
Since our exposure will be limited by the exposure needed for the foreground subject and since we want the longest time available to get a chance to capture a lightning strike, it is only obvious that our ISO setting is going to be the lowest available to us.
RAW or JPEG
If you are a JPEG shooter, then this is one subject that will force you to shoot RAW. A JPEG file cannot give you the exposure and WB leeway needed for processing a lightning shot.
Importance of Aperture size
Lightning strikes may seem powerful to the eye, but in practice are not that strong to be recorded by small apertures. This is why some trial and error is needed to judge lightning distance. The further away the lightning the more you need to open the aperture and the closer the lightning to more you can close the aperture. It’s good to avoid small apertures since lightning that is far away will not be recorded. Here is a rough estimate to get you started. With a 24mm lens and with lightning the height of nearly the whole frame, try f/5.6 –f/8. If further away with a height of half the frame, then start at f/4. Thankfully lightning strikes are usually repetitive for a certain amount of time in a certain direction so setting up your frame will not be that difficult. Also a DSLR is able to give you results straight away so after only a few shots you will have found what exposure to use. Generally a good starting point is 100 ISO and with an aperture of f/5.6.