Photographing the Lunar Eclipse

Rolling out of bed at 4am, gathering my equipment with a head still foggy with sleep, and driving thirty minutes to an open space preserve in Marin is not usually how I start a weekday. But this weekday was special – a total lunar eclipse would be visible in the west as the moon set (weather permitting).

I used PlanIt! Pro to research a location for the event. I knew I wanted to take a sequence of shots as the moon moved through the phases of the eclipse, so I’d be going somewhat wide, which meant I either needed to put an object in the foreground – an interesting tree perhaps – or some kind of landscape feature. I didn’t have time to scout, and I wanted to keep things simple in the early morning (less things to screw up) so I decided to make Mt. Tamalpais integral to the shot. The app helped narrow the locations down to Camino Alto Open Space in Corte Madera and Ring Mountain in Tiburon. Not wanting the moon to look too small in comparison to the landscape, I opted for Ring Mountain which was farther away from Mt. Tam, and figured on zooming in a bit with a focal length of 35mm on APS-C (about 53mm full-frame equivalent).

On top of the thirty minute drive, it’d be a thirty minute hike uphill from the trailhead. I wish I would have found time to visit Ring Mountain in daylight beforehand, as it was a challenge to get in position on time, and difficult to see in the dark. I chose a spot and stuck with it, but as dawn broke, I could see other locations that might have been better.

lunar eclipse above mount tamalpais

Once I was in position, the eclipse had just reached totality. I took some test shots and settled on f/5.6, ISO800, 4s. I changed this as the moon became progressively brighter, mainly through trial and error. I set a timer on my phone to help me take a shot every ten minutes. After about an hour, I took a series of frames to use for night sky stacking – a post-processing technique that helps clean up noise and color on dark skies – then resumed the moon exposures. Finally, as the moon reached the vicinity of Mt. Tam’s east peak, and blue hour began, I took some shots to capture a little more detail in the landscape. A scrim of hazy clouds diffused the light from the brightening moon and created an interesting rainbow halo.

The only issue I encountered was when the Earth’s shadow moved enough for moonlight to shine again. I exposed for the moonlight instead of for the shadowed area of the moon. If I get an opportunity like this again, I would rather overexpose the moonlight if it means I could recover some detail in the shadow, so that those exposures would look more consistent with the others taken in the sequence.

To process all of these images, I broke up the work into four parts: the night sky stack, the moon sequence, the blue hour landscape and the final composite. Some tutorials say to combine the moon exposures using the “lighten” blend mode in Photoshop, but I preferred the results of masking each moon instead. I did use lighten, however, when overlaying the city lights from the long exposure stack with the blue hour landscape. I then applied a gradient mask on those layers to reinforce the sense of time passing from night to dawn.

All in all, I’m happy with how the image turned out. But it’s clear that more thorough planning could have easily improved the final result.