I spent an evening in a remote canyon trying to get a good shot of fire spinning within the canyon walls. The shots did not work out so well, and as I was leaving, I noticed how many stars were in the sky above the river at the canyon entrance. I wanted to get a shot that both captured the faint star light, and the intense light from the fire spining. I set the camera on the tripod and took a few super high ISO shots that were too noisy to use, but that I could use to frame the shot in the dark quickly.
For the final shot that I wanted I knew that I could not do it with one shot, as the range of light was far too wide with both starlight and firelight. So I would have to take two shots.
I first exposed for the sky and canyon walls. I painted light on the trees, by shining a maglite on the canyon walls behind me. This bounced off the walls and into the frame, the rock wall behind acting like a large softbox to diffuse the light a bit.
This is the first shot:
30 Sec /// ISO 2500 /// f 2.8 /// 11mm
This gave me a good exposure for the sky and a bit of light for the foreground from the flashlight bounced light.
From the same spot, with the camera on tripod, I took a photo to expose for the fire spining. Far, brighter, the exposure was quite different.
30 Sec /// ISO 500 /// f 8.0 /// 11mm
I used Photoshop to screen the fire exposure over the forest image, so it added its light to the dark area of the image. I erased the sky of the fire image, so that no stars that had moved between exposures would show or blur.
The final image: