On my first day this year on Maui I was driving north of Kaanapali on Maui’s northwest shore, when a rainbow began to grow in the sky. At first it was a sliver rising from the agricultural foothills of the West Maui Mountains. But as I drove it grew in the sky until a perfect rainbow formed. Of course, I pulled over and even as I ran across some wet, waist-high sugar cane, the rainbow started to fade.
I had no time to set up a tripod or to grab a different lens. I shot with what was on my camera at the time, a 14-24 Nikkor on my D800. Despite the drizzle that started to fall, I managed six images, bracketing to allow for the fact that I had no filters at all on the lens. My setting for this particular image was ISO 200, 1/125 @ f11 with -1/3 EV.
I typically will shoot a rainbow with a polarizing filter on my lens, to accentuate the colors in the rainbow. However real life is seldom so simple, as my run through the sugar cane demonstrated. A photographer needs to be prepared for any eventuality.
I knew that I needed to increase the contrast, so I went to minus 1/3 EV. In other words, I bypassed what my meter was telling me by underexposing 1/3 stop (I also tried a shot at -2/3). I also bracketed my exposure just to be sure.
In post-processing, I darkened the sky by 1/2 stop and added +15 clarity to add more contrast and to slightly make up for the lack of a polarizer. That also had the effect of bringing out the clouds from the background sky.
I am not suggesting this is a great image; I have captured far better, far more dramatic rainbows in my time. But rainbows are like magnets. We are drawn to their enticing visual candy, yet another example of our incredible natural world.