Walking over to Yosemite Falls in the morning there was darkness and light. I was ready when the rainbow came out. I had my polarizer already on. I used a fast shutter speed and underexposed to emphasize the chiaroscuro effect.
The funny thing is that post-processing echoed conditions of this shoot. I layered in multiple RAW versions by the chiaroscuro light of my headlamp as the kids slept. I suppose I really should profile the combination of an LED headlamp and my laptop!