How to Photograph a Total Lunar Eclipse – PC Magazine
A total lunar eclipse is a spectacular event, and one that happens infrequently enough that it’s well worth going outside to gaze at. While you’re at it, bring along your camera and a sturdy tripod to mount it on. Although it can be challenging to get good eclipse photos because of the vast reduction of the Moon’s light during totality, with a little preparation it can be done.
A lunar eclipse occurs when the Earth lies between the Sun and Moon, and the Moon passes into Earth’s shadow. In a total lunar eclipse, the entire Moon is immersed in Earth’s umbra, the dark, inner part of the shadow. Unlike a solar eclipse, which is far too bright to look at (except through special filters) without risking blindness, it’s perfectly safe to look at all stages of a lunar eclipse.
The Challenge of Lunar Eclipse Photography
Photographing the early partial stages of a total lunar eclipse is much like photographing a non-eclipsed Moon. As a lunar eclipse occurs at Full Moon, photographing the onset of the partial phases is like shooting any Full Moon. Soon, though, you will have to compensate for the decrease in light as more and more of the Moon slips into Earth’s shadow. This is done by changing the ISO, f/ratio, and/or exposure time, while ensuring that the camera remains in focus. At the onset of totality, the reduction in light is particularly dramatic.
Stages of a Total Lunar Eclipse
The lunar eclipse begins when the Moon passes into the penumbra, the faint outer part of Earth’s shadow. If you were an observer on the Moon, from within the penumbra, you would see the Earth as partially covering the Sun. As viewed from the Earth, however, the penumbral phase of the eclipse is barely noticeable, if at all.
It’s only when the partial eclipse begins, and the Moon starts its slide into the umbra, the dark, central part of Earth’s shadow, that the action really starts. It will seem as if a dark bite is taken out of the edge of the Moon. (If you were on the Moon, within the “bite zone,” the Sun would be totally eclipsed by the Earth.) The bite grows larger, and within a half hour or so, half the Moon is in shadow. The light quickly dims, and soon the bright, sunlit part of the Moon will be but a thin crescent, with the rest of the Moon now faintly visible as a pale, ruddy glow. Then the crescent will shrink to nothing as the entire Moon slips into the Earth’s umbra, and the eclipse is total.
The total phase of a lunar eclipse can last up to 1 hour 45 minutes. Although no direct sunlight touches the Moon during totality, you can still see the Moon bathed in a faint reddish glow because Earth’s atmosphere refracts sunlight, and bends the light of Earth’s sunrises and sunsets around the limb of our world. Total lunar eclipses can vary greatly in brightness, with some appearing bright and coppery or orange, and others so dark that they’re barely visible. (Eclipses tend to be dark after major volcanic eruptions pump a lot of ash and dust into the air. During an eclipse, the Moon may not appear uniformly bright; often one limb will be notably lighter (or darker) than the rest of the Moon, and this may shift as the eclipse progresses.
As totality ends, one of the Moon’s limbs (the opposite from before) will appear as a bright thin crescent, and the phases described earlier will repeat, except in reverse, until the Moon is back to normal.
Ideally, you should have a digital SLR or a mirrorless interchangeable lens camera, and a lens with a relatively long focal length. (I’ve done most of my eclipse photography at 200 or 300mm.) You should be able to manually adjust settings such as white balance, ISO, exposure length, and f/ratio, as well as manually focus the camera. It’s helpful to have a LiveView mode to aid in focusing.
That said, you can still get decent photos using a compact point-and-shoot camera, provided it has some capacity for manual settings, particularly exposure length. Few basic point-and-shoots allow you to focus manually, but many have a setting for shooting landscapes at a distance (indicated by a mountain icon), which you will want to use. Point-and-shoots are best for astronomical landscapes, wide-field shots in which the eclipse is framed by foreground objects. For example, I shot the photo below on March 3, 2007 with a Canon PowerShot SD630 point-and-shoot. Point-and-shoots are also good for capturing the scene just before totality, when the Moon appears as a thin, bright sunlit crescent and the rest of its disk is lit with a pale reddish hue.
Because you will be using relatively long exposures to shoot a total eclipse, you will need to mount your camera on a tripod to keep it as steady as possible. It should be a sturdy tripod that can remain steady through wind gusts, and be sure to tighten all its screws.
Against the Dying of the Light
As the partial stage of the eclipse begins, settings should be what you might normally use to photograph a Full Moon. (Exact settings may vary considerably between cameras; typical settings for my Samsung NX300 with a lens with focal length set to 200mm are an exposure of 1/250 seconds at f/7.1 and ISO of 200.) You should set the white balance to Daylight (the sun icon). By the time that most of the Moon is in shadow and its visible face has become a crescent, you should boost the ISO to 400 and lengthen your exposure to 1/100 seconds. The brightness of the Moon’s image in your viewfinder or LCD should be your guide; as the image dims, you will want to shorten your exposure length. You should switch to manual focus because, for one thing, when the eclipse is total, its light may be too dim to trigger your autofocus. You should lower your f/ratio to f/5.6 or smaller; this will let in more light, but it will also decrease the depth of field, making it all the more important that you accurately focus the camera.
Shooting the Totally Eclipsed Moon
Although the crescent stage that precedes totality may seem dim compared with the uneclipsed Moon, the totally eclipsed Moon is much dimmer still. By the onset of totality, you should boost the ISO to 1600 or even 3200, if your camera can support that high an ISO without noticeably increasing noise. You should lengthen your exposure time to at least half a second, and monitor your focus from time to time to be sure that it remains sharp. As the total phase of a lunar eclipse can last well over an hour, it gives you plenty of time to experiment with your settings, with your guide being how the Moon’s image looks in your shots. If you’re using a lens with a very long focal length, it may limit your exposure length as the moon will move more quickly through your field of view. There are guided tripods, such as the Vixen Polarie, that will follow the Moon’s motion. A standard tripod using the Astrotrac accessory will do the same thing.
During totality, don’t forget to look away from your camera from time to time to gaze at the eclipse with your unaided eyes. It’s a rare and beautiful sight, and although it’s great to get good photographs of the eclipse, it’s no substitute for directly experiencing it.
When totality ends, you’ll once again see the sunlit portion of the Moon as a crescent, but this time the opposite side of the Moon will be lit. The pre-totality phases of the eclipse will repeat themselves, except in reverse, until the Moon is free of Earth’s shadow and the eclipse is over.