Shot from the roof of my house last weekend before the storm. Corrected some white balance and saturation because it got slightly blown out.

Settings:
ISO: 100
Focal: 18mm
f: 3.5
Aperture: 5s

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Well done for the capture, but next time try to get into a position where you cannot see any lights. That will enable you to use the "Bulb" setting and capture more than one lightening bolt

"f:" is "aperture:""

what you have listed as "aperture:" is in fact the shutter speed.

and as bob said use bulb, a small aperture, and a middle ISO.

that way you can hold the shutter open for a while (15-30 seconds) and not have to worry about lights in the picture as well. Use a tripod. If any lightning bolts strike in the 15-30 seconds, you have a cool shot. Otherwise try again.