On September 27, I photographed the total lunar eclipse, called a blood moon since the moon turns red. A total lunar eclipse occurs during a full moon when the sun, earth, and moon are in a line and the moon is close enough to the earth so that the earth blocks the sun from shining on the moon. Red light refracts the most. The moon in eclipse is reddish from the sunlight shining through the earth’s atmosphere and bending around the earth to illuminate the moon. A total lunar eclipse doesn’t occur very often — the next total lunar eclipse visible in California is in four years. A storm passed overhead, we were concerned we’d miss the total eclipse.
I joined a docent-led hike put on by a local open space district in the mountains forming the backbone of the San Francisco peninsula. The total eclipse would start before the moon rose in the east, so we hiked to a hilltop with an open view to the east. A mountain shielded some light from Silicon Valley.
We started early and had time to explore before sunset. Our hills are golden during our dry summer, reminding us that we’re the golden state. California is called the golden state because gold was discovered here in 1849. The Pacific Ocean is the shimmering sea in the distance on the right.
A small storm system was passing overhead, moving east. We wondered if the storm would pass by so we could see the eclipse. The photo below shows pink clouds and Black Mountain to our east at 7:06 pm, 10 minutes after moonrise. Pretty clouds, but we couldn’t see the the moon. The San Andreas Fault runs through this valley.
The total eclipse started at 7:11, but we still couldn’t see the moon. I snapped these photos at 7:55 pm to check if the camera could spot a faint glow that my eyes couldn’t see. The left-hand photo shows two small dots. I wondered if this was the moon. The longer exposure on the right shows the two dots as small horizontal blurs. I believe these are airplanes approaching the San Francisco Airport. The maximum total eclipse was at 7:48 pm, and we still hadn’t seen the moon.
For these moon photos, I tried auto exposure bracketing (AEB) for the first time. When the shutter button is pressed, the camera takes three photos separated by 2 EV: the nominal exposure, two stops underexposed, and two stops overexposed. I set the aperture at 7.1 and the ISO at 400, and the camera adjusted the exposure time to take three photos. AEB worked well, producing a set of photos where I could choose the photo with the exposure I liked. I cropped some images to make the moon larger, but I did no other post processing. The moon color in these photos is as-shot.
Despairing that we had missed the lunar eclipse, we hiked to another hill to catch a view of San Francisco. Then we got a call that the moon was out. We looked for the moon and hastily set up tripods and cameras on the trail. The clouds had continued moving east, and moon was finally visible over the treetops!
A minute later, clouds covered the top half of the moon. The clouds aren’t especially dense. I guess the moon is dim during a total lunar eclipse, so the clouds don’t have to be thick to obscure the moon.
By 8:19, you can see the bottom of the moon starting to brighten as the total eclipse is nearly over. We saw about five minutes of the total eclipse.
By 8:26 pm, you can see the sun’s rays on a sliver of the moon. The total eclipse has passed. At 8:57, half the moon is illuminated.
We hiked down the hill by the light of the full moon; I used my headlamp only in the shade of trees.
Reviewing the photos, I was surprised that many were blurry, since I used a tripod. These shots, taken at 8:20 with a 400 mm lens, show the blur. The 25-second exposure is the most blurry, with an oblong moon. Stars are parallel streaks. I think my shutter speed was too long, and the earth’s rotation caused the stars to move and thereby blur.
The AEB worked well, providing reasonably sharp photos from the -2 EV shot. The next time I photograph a total lunar eclipse, I’ll use AEB again, but I’ll open up the lens, constrain the shutter speed to about a second, and let the camera change the ISO to achieve the desired exposure.