The Making of "Lunar Eclipse over the Continental Divide"
Updated: Feb 15
From a photographer’s perspective, the moon is tiny. True, it’s 2,159 miles in diameter, but it’s nearly a quarter of a million miles away, so its angular diameter is just 0.5 degrees. To make it a meaningful part of your composition, you either need a long telephoto lens or you need a lot of moons.
That’s why I decided to shoot the May 15, 2022, total lunar eclipse as a “string of pearls” image. I’d lock the camera down on a tripod and make one exposure every five minutes from the time the partial eclipse began until the partial eclipse ended. Then I’d place all of the moons into one image that showed every phase of the eclipse.
This type of shot is simple in concept, but tricky to get right. First, I’d need to know where the moon would be at the beginning of the eclipse, both its direction (azimuth) and distance above the horizon in degrees (altitude). I’d need the same information for the moon’s position at the end of the eclipse. From that information, I could calculate the angle of view I needed both horizontally and vertically to include the moon’s journey through Earth’s shadow. The Pro version of Photo Ephemeris Web, an app which runs in a web browser ($30/year), had all the information I needed. During the May 15, 2022, eclipse as viewed from Rocky Mountain National Park, the moon’s azimuth would range from 119 to 162 degrees – a span of 43 degrees. Its altitude would climb from 3 to 27 degrees – a span of 24 degrees.
With that information in hand, I opened the field-of-view calculator in a mobile app called PhotoPills. A little guess-and-check showed that a 30mm lens on my full-frame Sony a7R IVa had a vertical angle of view of 43 degrees – enough to include the moon’s path through the eclipse plus some land below and a comfortable gap between the highest moon and the top of the frame. The field of view would be more than wide enough to include the complete eclipse sequence. Once the eclipse ended, I would need to continue making images every five minutes until the moon exited the frame.
With the basic parameters set, I next needed to decide where to go. The moon would be only 3 degrees above the horizon when the eclipse began. That meant I either needed to go somewhere flat, like the plains of eastern Colorado (too boring), or go somewhere high, like the summit of a mountain (much more interesting). If I was down in a valley, the moon would be out of sight behind a ridge when the eclipse began. In addition to going high, I needed to be looking southeast at something interesting.
I went back to Photo Ephemeris Web, the best photographer’s planning app that will run on a desktop or laptop computer. Maps are most useful when they’re big. Photo Ephemeris Web lets me plan shots on my 27-inch NEC MultiSync 272W monitor. With the app open in Chrome, I began exploring possibilities.
What would be the easiest way to get up high? Trail Ridge Road, which go