As a semi-seasoned eclipse veteran — I’ve traveled to five total eclipses, three of which were clear — I recommend that you take no photos at all. Just watch the spectacle unfold above you. Absorb every second. Total solar eclipses are not only rare for any particular locality, but when they do happen, the weather has to cooperate, too. During the upcoming August 21 eclipse, you’ll have about 2½ minutes to do the following:
- See the twinkling Baily’s Beads along the edge of the silhouetted moon immediately before and after totality. The beads are beams of sunlight poking out between the crater walls and mountains along the rim of the moon. When just one bead is visible the eclipsed sun looks like a diamond ring.
- Soak up views of the magnificent solar corona, the sun’s pearly, luminescent atmosphere, with the naked eye and binoculars.
- Examine the pink protuberances of flaming hydrogen called prominences poking from the edge of the blackened moon with binoculars or a small telescope.
- Look for the brighter stars, especially Regulus which will be located just a degree from the sun, and bright planets including Mars, Venus and (maybe) Mercury.
- Take in the strange twilight quality to the light and the dip in air temperature.
Now, if you add photography to the list, you’ll need to plan v-e-r-y carefully. Time goes by so quickly, you could miss much of the eclipse and have only a digital record of the experience if you pay too much attention to the camera. I like digital as much as the next guy, but visceral is preferable.
That said, I know that most of us will want to take at least a few photos. You can probably capture Baily’s Beads and a quickie photo of the moon silhouetted against the bright solar corona with a mobile phone, but a dedicated SLR camera on a tripod, preset to the correct exposure, and equipped with an intervalometer is the way to go.
An intervalometer is a device that hooks into the side of the camera that you can set to automatically snap a photo at a chosen interval, say once every two seconds. You set it up, press the button just before totality and let it take the photos, while you sit back hands free to enjoy the eclipse. You can find them for a variety of different cameras at B&H Photo, Amazon and eBay.
As far as exposure, I recommend you use this guide by eclipse expert Fred Espenak a.k.a. Mr. Eclipse. Fred’s guide will take you through lenses. sky coverage, ISOs, lens settings and exposures. One thing that may surprise you is how small the sun is. In a mobile phone it’s a dot and not much bigger when viewed through a standard 35 – 100mm lens. A longer telephoto, say 200mm to 500mm, works much better. Or you can hook your camera up to a telescope.
For photos of the partially eclipsed sun, you’ll need a safe glass or mylar filter to place over your camera lens to tone down its brightness and filter out retina-wrecking ultraviolet and infrared (heat) light. In the Solar Eclipse Exposure Guide table, Espenak’s provided shutter speeds for the partial phases using 4.0 and 5.0 neutral density filters. Safe neutral density filters for the partial phases are available from Orion Telescopes, Thousand Oaks Optical and Amazon. The sites also offer eclipse glasses for naked eye viewing before and after totality. Another naked eye viewing option is to purchase a #14 welder’s filter (and ONLY a #14, not a #13, etc.) from a welding supply shop.
Partial phases are easy because you have lots of time to take pictures — from start to finish the eclipse lasts about 3 hours. If the camera’s back display shows that the photo looks too faint or too bright, adjust you shutter or lens settings to find the optimal exposure.
The table is divided into ISO (the old “film speed”), shutter speed and f/number. F/number describes how much light your lens lets in. Low f/numbers (2.8, 3.5) allow in the maximum amount of light. High f/numbers (11, 16) much less. With low f/numbers, you can use faster shutter speeds; with high numbers, slower speeds.
To find the proper exposure on the table for any ISO/f-number combination, pick one you plan to use, then run your finger directly below the f/number to the Shutter speed table for a list of exposure times for capturing the many different aspects of the eclipse.
Things get interesting during the 2+ minutes of totality because the corona’s size and brightness vary according to how long you expose. When the moon completely blocks the sun, the exposure time goes up — a lot! Let’s say you’re photographing totality at ISO 400 with the lens set to f/5.6. To capture the innermost, brightest part of the corona you would expose at 1/2000″ to 1/500″. But for a photo showing the corona in its full glory, go for 1/30″ or longer. It’s up to you.
Once you set your camera, the intervalometer will do its job. Of course, you can change your exposure during totality, but it will distract from watching the eclipse. Keep in mind, that since the sun is moving slowly across the sky like on any other day, you’ll have to occasionally recenter it in the camera view. Or you can drop a few hundred dollars and purchase a tracking mount like this one and have it automatically track the sun.
When can you stare directly at the eclipse? Only when the sun is completely covered by the moon just as Baily’s Beads are winking out of view. For the duration of totality it’s perfectly safe to look at the eclipse. You’ll know when it’s ending and when it’s time to avert your eyes when you start to see the first flashes of Baily’s Beads long the opposite edge of the moon. Be cautious and have eclipse glasses or a welder’s glass at the ready at all other times during the eclipse.
I’ve assumed in writing this that you want to capture some of the partial eclipse and a telephoto view of totality. You can also use a wide angle lens and snap a scene with friends, trees, mountains. As you’d expect with a wide angle lens, the moon and corona will appear very small in your scene. As far as focus, you can use autofocus but make sure you point the camera somewhere around the edge of the moon where it’s silhouetted against the bright corona for autofocus to get a lock. You don’t want to mistakenly focus on empty sky.
Even though the quality won’t be as good, I’m thinking that holding your mobile phone to the sky might be the easiest and most foolproof way to get a photo. Just be careful zooming in — the heart beats faster as totality approaches, making it hard to keep your phone steady for tele photos. Shoot a few, then … be in the moment!