Sean Goebel
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Since 2019, I've had the idea of photographing a moonbow on Yosemite Falls while a hiker created a light trail up the trail next to it. My first attempt at this shot was canceled by the pandemic, and then the next few years were too dry for good moonbows. This year's record snowpack finally enabled this photo.
I wrote a Python code to predict where and when rainbows and moonbows could be possible. This involved some fun spherical trigonometry and vector math that I hadn't needed in a while. I was worried that I might have made an error and a whole group of people might make a trip based upon my erroneous predictions. Fortunately, my predictions were accurate, the moonbow appeared right on schedule, and it lasted about 20 minutes when viewed from Sentinel Dome.
A friend and I carried six cameras up to Sentinel Dome, across the valley from Yosemite Falls. Griff Joyce and Mark Vierra, of the Half Dome 50/50/50 adventure (https://sgphotos.com/photostories/griffhalfdome/) and the Yosemite lunar eclipse trip (https://www.flickr.com/photos/geekyrocketguy/52081544206), hiked up Yosemite Falls at the right time. An 82% moon illuminated the scene.
Clouds obscured the sky above, blocking the moon, and filled the valley, blocking my view of the falls. Following some desperate prayers, they cleared exactly as the moonbow occurred. The photo was possible after all!
Timelapse video: https://youtu.be/gD1cJzsTHMo
For each of the photos below, I stacked a bunch of 25- or 30-second exposures to produce the light trail. A single exposure was used for the moonbow.
Sony ILCE-7RM3A, Zeiss 100mm F2 Milvus, ƒ/2.8, 25 s, ISO 1250
Sony ILCE-7M3, Voigtlander APO-LANTHAR 50mm F2, ƒ/2.8, 30 s, ISO 1250
Sony ILCE-7M3, FE 12-24mm F2.8 GM @ 16 mm ƒ/3.2, 30 s, ISO 1600
The photo below was taken a couple nights earlier than my other moonbow photos. This was actually a test photo made possible by some rock climbers who fortuitously hiked down at night. I intended to shoot this angle with Griff and Mark on the trail simultaneously with my other moonbow photos. This camera spot is miles from the nearest trail, and basically no one visits it, so I placed a camera on the cliff with a note stating I would return and begging anyone who found it to not steal it. Unfortunately, I got quite unlucky, and some random off-trail backpackers found the camera. They didn't steal the camera, but they did move it and disable my timer. As a result, it did not collect the photos I wanted during the main moonbow shoot. On the other hand, the test shot came out well enough, and it resulted in this.
Sony ILCE-7RM3A, Sigma 14-24mm F2.8 DG DN @ 14.0 mm ƒ/2.8, 30s, ISO 2000
Before the trip, I prepared several simulated shots in order to help me plan my lens selection. For example, when I was on Sentinel Dome in February for the firefall, I shot the following photo with my 50mm lens. In Photoshop, I overlaid boxes corresponding to the fields of view of other potential lenses.
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