With the advent of digital cameras, photographing lunar eclipses has never been simpler or easier. Here are some tips on how to capture your own souvenir portraits of one of nature's most colorful and photogenic celestial spectacles.
If you've never recorded a lunar eclipse, you'll get a chance this Sunday (Sept. 27), when the full moon gets totally eclipsed by the Earth's dark shadow core, or umbra. It will be a so-called "supermoon" total lunar eclipse since the moon will be at perigee, its closest point to Earth in its orbit.
To find out if you'll be able to see the eclipse, check out Space.com's skywatching guide. Then use the following tips to photograph this amazing lunar event. [How to Photograph a Total Lunar Eclipse (Photo Guide)]
You will also be able to watch the lunar eclipse live online. The online Slooh Community Observatory will host a webcast at 8 p.m. EDT (midnight GMT) on Sunday. You can also watch the lunar eclipse webcast on Space.com, courtesy of Slooh.
Get a telescope or telephoto lens
To get dramatic close-up views of the eclipsed moon, you'll need a telescope or telephoto lens with a focal length between 500 and 2,000 millimeters. A 300-mm lens or scope will yield a lunar image that's only 3 mm across, just barely large enough to show surface details. You can boost the lens or scope's effective focal length by adding a 2× teleconverter or Barlow lens, respectively.
A telescope with a focal length of 2,000 mm produces a lunar image about 18 mm in diameter, which nearly fills the sensor of a full-frame, 35-mm-format digital single-lens reflex (DSLR) camera. But for many consumer DSLRs that use smaller APS-C sensors, this image size is going to be a bit too large, with the edges of the moon getting cropped in the camera frame. To remedy this, use a focal reducer to make the lunar image fit within the frame, or switch to a telescope with shorter focal length, say, 1,200 mm.
Use a tripod
Be sure to mount the telescope or telephoto lens on a sturdy tripod for stability and to minimize camera shake, which will blur the images. You can reduce vibrations even further by locking the DSLR's viewfinder mirror up and using an electronic "cable release" to operate the shutter button. A good alternative would be to use the camera's built-in delay timer to open the shutter.
Carefully focus your telescope/camera combination to obtain sharp images of the moon. Many DSLR cameras now offer "live view" mode, which allows you to see what the camera sensor sees, using its built-in LCD screen. You can zoom in on the image up to 10× magnification to check its focus.
Use digital, experiment with exposure
The greatest advantage of digital cameras over film for shooting the eclipse is that you get instant results. You can see what the image exactly looks like by reviewing it on the camera's LCD screen. Does the image look overexposed or out of focus? Not a big deal. Simply adjust the shutter speed or refocus the telescope and try again. Memory cards are now dirt-cheap, so it costs practically nothing to take dozens or even hundreds of photos of the upcoming rare event.
Nobody knows for sure how bright, or how dark, the moon is going to be during totality since it varies significantly from one eclipse to the next. So the best advice would be to "bracket" your exposures, that is, shoot as many images as you can using various exposure settings. Don't be afraid to experiment to find the best combination of aperture, shutter speed and ISO sensitivity for your particular setup.
Remember, the eclipse will start with a dazzlingly bright full moon. The moon then dramatically dims as the eclipse progresses, appearing dimmest around mid-totality. Afterward, it gradually regains its brightness, and the moon becomes full again as the eclipse ends. By taking lots of pictures, you'll increase your chances of catching some really good shots. You can also assemble the series of images to create an animation of the eclipse.
During totality, keep your exposures as short as possible by boosting the camera's ISO setting to 400, or even higher. This will prevent the image from smearing due to Earth's rotation, especially if you are using a fixed tripod. To extend your exposure time to a few seconds and capture the rich red and orange hues of totality, use a motor-driven, polar-aligned equatorial mount to accurately track the moon as it moves across the sky. [Total Lunar Eclipse of Sept. 27: A Complete Skywatching Guide]
Shooting the eclipse with a smartphones
Today's latest generation of smartphone cameras are capable of taking stunning photos of the moon. However, since you can't remove or replace the lens of smartphone cameras, you'll have to use the so-called "afocal projection" method to shoot the eclipse. It sounds intimidating, but it's really not. It simply means you have to aim the phone camera directly into the telescope eyepiece to take the shot. One advantage of afocal photography is that the telescope will greatly increase the effective focal length of the setup so you can capture decent-sized images of the moon even with a smartphone.
Holding the smartphone by hand is the simplest, though not necessarily the easiest way, to aim the camera. The biggest challenge is to hold the phone and try to keep it as steady as you center the moon in the camera frame, focus on the lunar surface and press the shutter button. Since the moon drifts steadily across the telescope's field of view when you're using a stationary tripod, you only have a half minute or so to take the exposure before you'll need to re-adjust the telescope and camera to keep the moon aligned with the eyepiece and camera lens.
For best results, purchase a commercial bracket or adapter from camera retailers or sporting goods stores that sell optics and accessories for hunting or birding (bird-watching enthusiasts call afocal photography "digiscoping"). Alternatively, do-it-yourselfers can make their own custom mounts. Whatever your choice, make sure the bracket or adapter will fit your eyepiece and will hold the smartphone securely. Be sure to focus the telescope visually first before mounting the camera. If you see vignetting, or darkening around the edge of the image, that means the camera is positioned too far from the eyepiece. To reduce vignetting, move the camera as close to the eyepiece as possible while keeping it centered.
Zooming in can also help eliminate vignetting and increase the image size. But don't overdo the zoom function — smartphones generally use "digital zoom" to simply enlarge the camera's picture elements, or pixels, but doesn't improve the image's resolution. You can use the phone camera's autofocus and auto-exposure modes to take the images, or if you prefer, you can adjust the settings to some degree yourself (check the camera manual on how to do this). There are also third-party camera apps you can purchase that will let you control the exposure and edit the photos.
Finally, make sure the smartphone is fully charged since you will be using the LCD screen all the time. Cold temperatures will also cause the battery to lose its charge quickly.
Since the images are stored in your smartphone, you can email, text or share them via social media right away.
The key to imaging the total lunar eclipse is to keep on shooting. If you don't like what you get, make the necessary corrections or adjustments and shoot again. Unlike a total eclipse of the sun, in which totality lasts only a few minutes, or seconds, during this Sunday's total lunar eclipse the moon will be immersed in the Earth's shadow for more than an hour, so you can just keep on trying until you capture a "keeper."
Most important, take a few moments in between exposures to enjoy the eclipse with your naked eye or through binoculars. No photo or video can compare with the real thing, so try to enjoy it visually, too.
Good luck and clear skies!
Editor's note: If you capture an amazing view of Sunday night's total lunar eclipse that you'd like to share for our upcoming column or image gallery, send the images to managing editor Tariq Malik at email@example.com.
Veteran astrophotographers Imelda Joson and Edwin Aguirre have observed more than a dozen lunar eclipses together since their very first one — a penumbral eclipse on July 27, 1980 — which they viewed from the Philippines. Follow us @Spacedotcom, Facebook and Google+. Original article on Space.com.