Lightning Storm Part 1

We had a really incredible thunderstorm roll through last night. For about half an hour there was an awesome lightning show. I took 64 photos, each with an exposure of 30 seconds, which covered the majority of the storm. Of those, I kept my best 27 with the most lightning strike captures and least rain on the lens. (I had to keep wiping the lens clean in between shots!) Here is my favorite image:

I thought I’d write a short tutorial on how I captured the above image. Lightning is very fast and very bright. Faster and brighter than fireworks, especially if it is close. There is no way to predict where or when it will strike, so a long exposure is necessary to capture it. You could never trip the shutter fast enough if you tried a short exposure, the lightning would be gone before the shutter even opened! By using a long exposure time, you increase the chances that you will capture a strike while the shutter is open. Of course, a long shutter speed necessitates a tripod, so that is the first piece of gear you will need. Second, since you don’t know where it will strike, a normal to wider focal length is handy to capture more of the scene and also increase your chances. For these images I used a 24-70mm f/2.8 on my Nikon D700, a full frame 35mm sensor. If you have a crop sensor you’ll have to figure out the multiplier and go from there (typically 1.5-1.6x on a DSLR). I was going to use my 14-24mm f/2.8 for a much wider angle, but the front lens element really sticks out on that lens with very little protection of a lens hood. I figured I’d get more rain drops than lightning bolts, so I stuck with the 24-70mm! I started out at 24mm wide for half of the photos, and then zoomed into 31mm and 40mm for the remainder when the storm started to move off into the distance. My favorite image above was taken at 40mm.

I should pause a second and insert a disclaimer here: shooting with an aluminum tripod in a field during a lightning storm and soaking your camera in a driving rain is probably not wise. 🙂 However, you gotta go where the light goes, and the best photos aren’t usually of the mundane that we see every day. I had a house with a metal roof near me that I hoped would be more attractive to a stray lightning bolt than my tripod, and my camera is pretty weather sealed, though I had it covered with a waterproof rain jacket regardless. I also waited and took a few photos from inside when the lightning was directly overhead, and ventured out after I could tell it was a few miles off by the thunder. Good time to setup the tripod, choose a lens, and change camera settings though.

Back on topic, here are a few camera settings I changed. I disabled auto focus and focused manually to near infinity. I know where my camera autofocuses on the tree line from where I was during the day, and it’s just a whisker before infinity on the lens. I didn’t want the camera trying to autofocus on a dark sky and missing a shot. Next I put the camera on manual exposure metering; program, aperture, or shutter priority would just confuse the camera. I disabled auto ISO and set it to 200. I raised it to 400 for a few shots once the lightning was less intense and the sky was darker. I used a 30 second exposure to give myself as much time as possible to capture a lightning strike in each image, preferably several strikes. I used f/8 to f/16 for an aperture, depending how bright, close, or frequent the lightning bolts were. I shot in RAW mode instead of JPEG for easier editing later on the computer, and more dynamic range in each image. Since I was shooting in RAW mode I left my white balance set to auto. The D700 does a remarkable job in auto white balance, and you can change it in post if you shoot RAW. I later changed it to daylight/cloudy in post to warm up the sky a bit and get some nice purple hues. If you shoot JPEGs, I would try daylight/direct sun or daylight/cloudy and see if you like the results on your LCD preview. You could use a remote shutter release if you have a bright foreground object that you would like sharp with no movement, like city lights. It didn’t matter much in my case since I was shooting complete blackness except for the lightning strikes. I also disabled long exposure noise reduction in the camera. This would have helped remove some hot spots that I had to deal with back on the computer, but I also would have taken half as many photos during the same time period and missed a lot of good strikes. The compromise was worth it to me.

That’s about it for camera settings. Let me explain what is really going on here and why these settings. The aperture is choosing the intensity of the lightning; since it strikes so fast and is gone in a blink the shutter speed doesn’t matter to the brightness of the bolts. The shutter speed is really only controlling how many strikes you want in your photo, depending on the frequency of the lightning. The ISO is primarily controlling the brightness of your sky and clouds. Actually, both shutter and ISO contribute to the sky and background, but you’ll find it easier to set your shutter first to the length of time you need to capture as many bolts as you want, and then change your ISO to get the sky and clouds as bright or dark as you desire. If there are too many lightning bolts in your images, shorten your shutter speed. If there aren’t enough, lengthen it. Most cameras can’t go beyond 30 seconds without an external remote, and you’ll start getting a lot of noise from sensor heat past 20 seconds or so if long exposure noise reduction is disabled. If your lightning bolts are too bright, choose a smaller aperture like f/16 to f/22. If they are too faint choose a larger aperture like f/8 to f/11. If the clouds are too dark choose a higher ISO like 400, if they are too bright or you have a lot of city lights, choose a lower one like 100-200. I find it easiest to set the shutter speed first, then aperture, then ISO until I like what I’m seeing on the LCD.

In a follow up article I’ll explain what I did in post-production for HDR and how I stacked 15 images in Photoshop to get more lightning bolts in a single image.

Happy shooting and stay safe!

These images can be purchased through my gallery here:
http://galleries.aaronpriestphoto.com/Night/2011-08-01/

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