When photographing a lunar eclipse using the wide-angle technique, you’re capturing one instant of the eclipse. When using the Star Trails technique, you’re capturing several hours of the eclipse in one frame. The Multiple Exposure technique combines the best of both, by capturing a sequence of individual images that show the eclipse throughout its different stages.
Using a digital camera, you will be making a series of exposures, which will each be saved as individual files in the camera. In post-production, using software such as Adobe Photoshop, you can combine or “stack” the image files into one image that shows the series of small moon images each illustrating a different phase of the eclipse.
Starting Exposure: To make multiple exposures during a lunar eclipse, camera set up and orientation is identical to the Star Trail method. But instead of taking one long exposure, you’re going to be taking a series of short exposures during the various stages of the eclipse. It is essential that the camera be on a sturdy tripod and not move throughout the eclipse.
Make the first exposure as the partial eclipse begins and then shoot additional exposures every 5 to 10 minutes. Be consistent and use the same time interval between shots so your final image will have the moon evenly spaced as the eclipse progresses.
Since the moon’s brightness varies during an eclipse, you will need to change the exposure throughout. Click here for Mr. Eclipse’s Lunar Eclipse Exposure Guide, which will help you determine the correct exposures for each phase of the eclipse, based on the ISO and f/stop you have selected.
For example, let's say you're using ISO 400 at f/8. The guide recommends a shutter speed of 1/1000 second as the partial eclipse begins. The shutter speeds for eclipse magnitudes (brightness) 0.3, 0.6, 0.8 and 0.9 would then be 1/500, 1/250, 1/125 and 1/60 second, respectively. Whatever exposures you use, it’s best to bracket one full f/stop around the recommended value. This is easy to do if you set the camera for bracketing before the eclipse begins.
To capture large images of the moon during a lunar eclipse, you will need to use a long telephoto lens or a telescope. You can also use a COOLPIX P&S digital camera with a superzoom. With a D-SLR, you can also combine a super telephoto lens with a Teleconverter to increase the focal length. You can also increase the relative size of the moon's image in an FX format camera by selecting DX Crop Mode.
There are many telescopes that will allow you to connect a camera, using an adapter. Using a telescope that has an equatorial mount and electric clock drive that counteracts the Earth’s rotation allows you to automatically track the sun, moon and stars for long exposure Astrophotography.
Starting Exposure: The Lunar Eclipse Exposure Guide is a good starting point for photographing the moon during a lunar eclipse using a telephoto or super telephoto lens or telescope. Bracket your exposures by under- and over-exposing by one or two f/stops to ensure that you get a perfect exposure. To capture a good sequence of photos, you’ll probably want to take the bracketed series of exposures every 10 minutes.
During a total eclipse, the moon’s color and brightness can vary enormously, taking on hues ranging from bright orange, to deep red, dark brown or grey. The color is due to the indirect sunlight that is refracted through and filtered by the Earth’s atmosphere before reaching the moon. You can also use your camera’s Spot Meter to take an actual meter reading of the moon and bracket your exposures from that point.
© Fred Espenak