Lightning at Onkaparinga Mouth by Frances Allan
The basics
Lightning arises from cumulonimbus clouds when the base of the cloud becomes negatively charged. Only 25% of lightning will discharge from the cloud to the ground. On average, a severe thunderstorm can produce approximately 6,000 lightning strikes every minute.
The problems encountered in photographing lightning are numerous. How do you know when it’s going to happen? It can be very dark in a storm, but a lightning bolt can be hotter than the surface of the sun. What exposure do you use? What is the best location?
Location
Map of Australia showing the frequency of Thunderstorm days.
Most lightning occurs in the tropics (70%). The place with the most lightning strikes on this planet is a small village of Kifuka in the mountains of the eastern Democratic Republic of the Congo. The combination of a tropical climate and high altitude results in a high number lightning strikes, occurring on more than 260 days of the year. Other hotspots include, Lake Maracaibo in Venezuela , Singapore, and Lightning Alley in Central Florida.
In Australia the best place to see lightning is around Darwin with over 80 thunder days per year, mostly between November and March. In Adelaide we have less than 15 thunder days a year. Our best chance for lightning is during summer storms between the months November and January.
If you want to photograph lightning you need a good clear view of the sky. A lot of people choose an open plain or a view over the sea. An interesting foreground feature is a bonus. (I would love to have Uluru in front of a lightning storm).
The distance to the storm can be calculated by timing the gap between lightning and thunder. Every 5 seconds represents a km. As the storm approaches it is important to keep out of harms way. Do not stand on hills, under trees or with your feet in water. The lightning will be conducted around the outside of a tree and will harm those standing underneath. Do not talk on the land line or the computer. Talking on a mobile is OK. Sitting inside a building, or a car is a safe spot.
Tripod / hand held
A tripod is advisable. Particularly when shooting at night. Also a tripod gives you the opportunity to use a long shutter speed (30 seconds or more) to increase the chance of capturing a strike. While the shutter is open I sit there poised ready to press the shutter release again, for the next shot, immediately after it closes. I want to get off as many shots as I can to increase my chances of capturing a strike. I will turn off long shutter speed NR in order to avoid delays. During the day time you may use a Neutral density filter to reduce the in coming light, and lengthen the shutter speed.
One night I was caught out in a storm in the city without a tripod. I steadied myself against a tree (obviously not heeding my own advice) and took multiple 1/2 second exposures until I captured a strike. I think that was the slowest I felt that I could hand hold against a support. I had only one successful shot out of perhaps 50 shots taken. It was however sharp enough and a very pleasing image (above).
Focus
Of course it is hard to focus the camera at night. The trick is to find a bright but distant object, like a distant building or the moon or a star. Use autofocus to achieve sharp focus and then slip the camera into manual focus to lock this setting. Eric reminds me you can always go into manual focus and dial up infinity, ∞ and correct any imperfection by closing down the shutter to increase depth of field. You must remember that modern cameras will focus past infinity, so turn the dial to the middle of the infinity symbol ∞, and not until it stops turning.
Shutter release
As mentioned previously we will select a long shutter speed to maximise the number of strikes that we can capture. The simplest would be shutter priority, but manual mode is an excellent alternative. In manual mode you can select bulb, and leave the shutter open for extended periods. In this case I use my wrist watch or phone to time the exposire.
Some cameras can be equipped with light sensitive triggers that can be utilized for lightning photography. These triggers come into their own for day time thunder storms. Alternately live view allows the shutter to be released by a computer or mobile phone with software like digicam control. The new Sony mirror-less cameras have interesting low light capacity that allows a scene to be built sequentially from shorter exposures. No need to worry about exposure, just close the shutter when the image on the screen meets your expectations.
Exposure
It is reasonable to expose for the night scene and hope that the lightning doesn’t blow out or get over exposed. You can hedge your bets to a degree by shooting in RAW so that you can adjust back the highlights in post processing. Alternatively you can use exposure compensation to eke the exposure back 1 to 2 stops in anticipation of the brightness of the lightning. The lightning may be far off when you first start shooting, requiring no exposure compensation. As the bolts come closer they will be brighter and you may have to increase the exposure compensation as the night proceeds.
Post Processing
Once on the computer you may want to tweek the image in lightroom or photoshop to maximise the dynamic range. I am amazed at how many little tendrils of lightning there are in the sky, when to the naked eye all I could see was a single bolt. I find it pleasing to have both shape in the cloud and am intricately textured lighting bolt. If the exposure is too bright the lightning becomes a big white shapeless blob, like a blown out sunset. If the exposure is too dark, you lose all interest in the sky and the location that you chose. In Camera Raw you can very easily darken highlights and brighten shadows to achieve this effect. Alternatively a HDR program like NIK filters can resolve the range using tone mapping. Saturation and sharpness can be altered, but beware of using a heavy hand, like salt and pepper, they can be easily overdone.
Well I hope these tips are useful as you endeavour to take a better lightning photograph. Best of luck.
Camera Clips 