Star Trails over Old Faithful

I first encountered Fernando Boza's great shot of star trails over Old Faithful several years ago. It inspired me to go to Yellowstone in February 2016 with one goal: to create an image of Old Faithful erupting at night, lit by the full moon, with star trails circling around Polaris directly above the towering column of boiling water and steam. I anticipated lots of technical challenges: figuring out the correct exposure for Old Faithful at night, putting together the frame containing the correctly exposed geyser with all of the frames containing star trails, and preventing condensation on the lens during the two-hour series of exposures. What I didn’t anticipate was getting stared down by a 2,000-pound bison. Fortunately, losing the battle of wills with a bison forced me to find a still better composition than the one I originally had in mind.

Initially, I had envisioned placing the geyser in the center of the frame, with Polaris directly above. I rarely aim for simple symmetry in my compositions, but in this case I thought it would be pleasing. When I arrived at Old Faithful, however, I discovered that a group of bison had bedded down for the night not ten yards from where I wanted to plant my tripod. The legal (and safe) limit for approaching a bison is 25 yards. Every year tourists get gored by bison in Yellowstone. Bison are so strong they can toss a person into the air with a single thrust of their massive horns. I backed off and began searching for an alternative composition.

Fortunately, a light snow had fallen the previous day. Warm water flowing away from the geyser had created a meltwater channel, which served as a leading line that took the viewer’s eye into the frame and toward the geyser, which I placed in the lower right corner. That put Polaris left of center, creating an asymmetric but dynamically balanced composition.

After a complicated series of calculations (see my blog post The Making of Star Trails over Old Faithful for details), I arrived at an exposure of 10 seconds, f/2.8, ISO 1250. I attached an intervalometer and began making ten-second exposures back-to-back. In a final stroke of good luck, the wind blew from right to left when the geyser erupted half an hour later, pushing the steam into the frame rather than away from it. When I returned home, I spent many hours experimenting with ways to assemble the 615 frames in the series, finally arriving at the image you see here.