Photographers from around the world have Yosemite National Park firmly planted on the top of their bucket lists, with the naturally occurring “firefall” phenomenon among the most spectacular events to witness there. This year, between Feb. 15 and 19, I was able to photograph one of the most spectacular firefalls ever recorded, due in part to El Niño.
In mid-February each year, a celestial and terrestrial convergence occurs between the setting sun and Horsetail Falls, a 1,570-foot waterfall located on the eastern edge of Yosemite Valley’s famed climbing wall, El Capitan. The event is quite rare because it depends on simultaneous factors working in unison, like a wave that only breaks perfectly once a decade. This is the stuff that makes life so amazing.
The first factor: Horsetail Falls must be flowing. By comparison, Yosemite Falls is the world’s fifth tallest waterfall, fed by almost 32,000 acres of watershed. During the recent drought, Yosemite Falls dried up.
Horsetail Falls begins at an elevation of 6,100 feet and is fed by a small 30-acre area that lies between 6,200 and 7,600 feet. Even when there is enough snow, it might not be melting. When Horsetail Falls is not flowing, the firefall doesn’t happen.
The second factor is the angle of the sun in relation to El Capitan and Horsetail Falls, a term known as the “azimuth.”
Thanks to the intricate predictability of celestial movement, we know the sun will always be in the correct position for the firefall at some point during the second and third weeks of February. When the sun sets with an azimuth between 246° and 263°, sunlight will hit the falls.
Solar events have influenced culture since the dawn of time. The sun was worshiped as a god because it is the ultimate energy source, guiding ancient societies like the Mayans and Aztecs when to plant their crops and repeat their religious ceremonies. The sun has the same effect today, sending hordes of professional and amateur photographers to Yosemite to see the show.
The third factor is the prow, or prominent front edge of El Capitan, which protrudes in such a way that a shadow is cast on the mountain’s entire eastern face at exactly sunset, except Horsetail Falls. The setting sun barely squeaks by during these few weeks in February and only when the cloud cover near the horizon allows it.
Which leads to the fourth factor, clouds. When the horizon is completely clear of clouds, the sunset light is typically orange. No clouds at all and good snow melt conditions, like a hot afternoon on a clear day, mean you’ll probably get lucky and see the typical orange glow of the firefall, which really does look like flames. Light or patchy clouds on the horizon and in the sky can create refracted sunlight and, when combined with atmospheric gasses, make intense pink, red or even purple sunsets.
Each year, despite being in the right place at the right time, hundreds of observers head back to their RVs and campsites disappointed because the sun never made its way through the clouds.
If you happen to be in Yosemite after a clearing storm and the clouds are sparse but present, you could be in for an epic firefall like the few I got to witness. That’s the “luck” factor.
Tips for photographing the Firefall
Use a tripod, the best one you can afford. Since you will be shooting this scene in low light from a few thousand feet away, you will need to stabilize your camera if you want to come away with sharp results. I often weight my tripod down with my camera bag or a sandbag to prevent a breeze from moving the camera once it’s mounted.
Use a low ISO. Ideal is 100, or if your camera will do it, 64. This will require a longer exposure but will yield less grainy results as long as your tripod is stabilized and your camera is properly focused. Using the self-timer setting or a shutter release cable is always a good idea when taking low light photos.
Consider using a “critical aperture.” All lenses have a sweet spot. As a general rule, two stops from the widest aperture of your lens is the sharpest. If you have an f/2.8 lens, two stops would be f/5.6. If you have an f/5.6 lens, two stops would be f/11. A great way to find out what aperture is the sharpest is to test it. Google, “What is the sharpest aperture on a lens?” to find out how to test your lens.
Shutter speed will be determined by the light meter’s reading once you set your ISO and aperture; go with whatever properly exposes the scene. Every camera will be different based on the sensitivity of its sensor and the available light.
Metering. I used “spot” metering as opposed to “matrix” metering because I wanted to properly expose the waterfall light, not the whole scene as you would normally do in a landscape situation. The result of metering the falls rather than the whole scene means that the surrounding rock of El Capitan will be darker, which makes the waterfall light pop off the rock face.
To find out more technical information about the celestial positioning involved in taking photographs, check out the Photographers Ephemeris smartphone app.