View more of Sean Bagshaw's photography and read his photo blog at www.OutdoorExposurePhoto.com.
Since the beginning of human existence night sky events have inspired in us wonder, awe, inquiry, fear and superstition. Solar and lunar eclipses are particularly inspiring because they affect the largest and most important objects in the sky, the Sun and Moon. Armed with some basic knowledge they also provide us with a real-time opportunity to observe and understand the motion, relationships and interactions among the Earth, Sun and Moon. Solar eclipses (the Earth passing through the Moon's shadow) happen less frequently than lunar eclipses (the Moon passing through the Earth's shadow) and, due to the harmful effects of staring at the sun, are also harder to observe directly. Lunar eclipses occur about twice a year and, other than happening in the dark, are easy and safe to view. As such, they provide an excellent photography opportunity, one that can yield great documentation of a cosmological event and, with a little creative vision, compelling artistic imagery.
On August 28, 2007 a total lunar eclipse was visible from the western portion of North America. With clear skies and summer temperatures in the forecast a photographer friend, Dane (www.inner-light-images.com), and I decided to take the opportunity to try our hand at photographing the event. Even though lunar eclipses are common on a cosmic scale, they are rare enough in the course of a photographer's career that there might only be a few chances to be in the right place at the right time to photograph one. Neither my friend nor I had photographed one before, so a little research and education was in order. There are many good sources of information on lunar eclipses on the Web. The following two links were particularly helpful in preparing to capture the eclipse on camera.
A lunar eclipse only occurs during a full moon because that is when the Moon is situated directly opposite the Sun with the Earth in the middle allowing the Earth to cast its shadow on the Moon. An eclipse doesn't occur with every full moon because the Earth casts a shadow along a plane in line with the Sun, but the Moon's orbit only crosses some portion of that plane two to four times per year. The rest of the time the full moon is either above or below the plane of the Earth's shadow and no eclipse occurs. Additionally, a full moon can only be seen at night due to its location opposite the sun. This means that even if an eclipse happens, you must be on the night side of the Earth to observe it. The day side of the Earth faces the Sun and faces away from the full moon, so people on the day side of the Earth during an eclipse will not be able to see it. The NASA link above provides some excellent diagrams showing how this works.
Photographing a lunar eclipse presents some challenges, but due to the slow speed and predictable nature, it is possible to prepare before hand and do a lot of trial and error while photographing one. The first challenge is being in the right place at the right time. Some enthusiasts will travel to a place on the planet where it is known an eclipse will be visible. Others, like myself, wait until an eclipse will be visible where they live. Weather is another challenge. If the sky is cloud covered the eclipse will not be visible. Many eclipses occur late in the night and getting out of bed can be a particular challenge for some. Also, a total eclipse can last up to several hours from start to finish, so some commitment and patience is required to photograph the entire thing.
Photographically speaking there are several considerations to take into account when preparing to photograph a lunar eclipse. To see the surface of the moon with a great amount of detail, a large telephoto lens is necessary. Lenses in the range of 300mm to 500mm will enlarge the moon enough for sufficient detail, but even larger lenses or small telescopes fitted for photography are needed to get a full frame image of the moon. A wider angle lens can be used with a film camera to take multiple exposures of the moon on a single piece of film. If exposures are taken every ten minutes or so, the final image will show the actual arc of the moon in intervals throughout the period of the eclipse. Most digital cameras aren't able to take multiple exposures in one image, so to get this affect, individual exposures of the moon must be taken and then placed together in an arc in a computer using image editing software like Photoshop. For my image of the full eclipse arc I took photographs about every 10 minutes during the five hour duration of the eclipse. Then I selected 20 photos that I felt made a good sequence. In Photoshop I cut the moon out of each imaged, sized them and placed them in an arc on a black background. Then I superimposed the moon arc onto a foreground image that I took from the same location on the same night. The final image does not show the actual path of the moon in the sky, but does give a pleasing and somewhat accurate representation of the event. I chose to include the pre-dawn colors on the horizon for artistic affect even though a full moon is actually located directly opposite the rising sun.
Regardless of whether you want to take close-ups or a wide angle, multiple exposure image, you will need to be prepared to adjust the length of exposure as the eclipse progresses. A fully lit full moon is very bright and has the same exposure requirements as sunlight on rock (since that's what it is). But, as the shadow passes over the moon and the light shifts from direct light to indirect light, the exposure times will lengthen considerably. For the completely lit full moon my exposure times were 1/400 of a second at f/5.6 with an ISO setting of 100. As the Moon passed further into the Earth's shadow the exposure times became longer. I bracketed my exposures on almost every image to make sure that I had at least one image in which the moon was properly exposed. Eventually I reached an exposure time of one second. From calculations made before the shoot (with help from THIS website), I knew that with a 400mm lens, any exposure time longer than one second would not be fast enough to stop the Moon's motion in the sky, resulting in a blurry image. To maintain my one second maximum exposure time I began to adjust the ISO instead of my shutter speed to offset the drop in light. In digital cameras, ISO is the measure of how sensitive the sensor is to light. Higher settings are more sensitive so they would allow me to maintain my one second exposure time, even though the Moon kept getting darker. However, higher ISO settings also introduce noise into a digital image, so I wanted to keep the ISO as low as possible to minimize noise. When the Moon was completely within the Earth's umbral shadow (totality) my exposure was 1 second @ f/5.6 with an ISO setting of 640. Then as the Moon passed back out of the shadow I reversed what I did during the first half of the eclipse.
Many people have asked me about the color of the Moon when it is in totality. This particular eclipse featured a beautiful brick orange/red color. The color is determined by the way light is refracted through particles and clouds in the Earth's atmosphere as it curves around the surface of the Earth. Depending on cloud cover, pollution, fires and recent volcanic activity, the color of an eclipsed moon can vary from light orange to brick red to dark brown. The difference in brightness between the lit and shadowed portions of the Moon during partial eclipse is so great that a camera can not "see" both the dark and light side at the same time. However, the human eye can, so when we observe an eclipse we see the reddish shadow advancing across the bright face of the moon but we see detail in all areas. What a camera sees is either the red shadowed side with the light side completely white, or the light side with the shadowed side completely black. By blending two different exposures of the moon in Photoshop, I was able to create an image that shows detail in both the shadowed and lit portions of the Moon during partial eclipse, much closer to the way it would appear the human eye.
I hope you have enjoyed viewing my lunar eclipse photography and found the information on eclipses and how to photograph them helpful. My lunar eclipse photos are available as signed art prints as well as more affordable special editon poster prints. If you are interested in purchasing a signed art print or a special edition poster, please contact me HERE.