Did you remember hearing about Comet ISON in December? It was meant to be the brightest comet seen in our skies. What was supposed to be "The Comet of the Century" fizzled out as it shot past the sun at a range that was clearly a little too close for comfort. Now it's just some dust and debris. No one is more disappointed than us astrophotographers. Well, maybe the folks at NASA, but we astrophotographers are pretty disappointed too. So much for "The Comet of the Century."
The good news is, naked-eye comets are not so rare that you've just forever missed out on a golden opportunity to get some astounding photographs. In fact, if you know where to look, there are a number of comets visible this year. With a little bit of know-how you can get some great photos of comets. Here's how.
[ Top image Comet Lovejoy (C/2013 R1) by Flickr user Paul M. Hutchinson FRAS]
What you'll need
A tripod and a cable or remote release (or a self-timer) is an absolute must for nearly all comets, except of course for those rare "daylight comets," which are bright enough to be viewed during the daytime with the naked eye. Sadly, daylight comets are so rare that there have only been nine of them in the last 332 years--which probably explains why they made ancient people behave so irrationally (daylight comets were usually thought to prophesize some awful event). Some people thought Comet ISON was going to be the 10th daylight comet we've seen since that somewhat arbitrary-seeming number of years ago, but then it had to go and get burned up by the sun. Stupid comet.
Apart from that tripod, you really just need a good DSLR and a lens with a focal length of at least 100mm, though obviously the longer your lens the better your shot will be.
Poor, doomed ISONtye-iacOT-jcc-ISON-003 by Flickr user starryearth
If your comet is visible in the morning, and you are lucky, you can just roll out of bed and set up your tripod and camera in your backyard. Or even better, through your open bedroom window while sitting on the floor in your pajamas. Most of us aren't that lucky, though. If you don't have a perfect view of the night sky from your house in the country, you'll have to travel someplace away from light pollution, where there aren't any trees, mountains or other large objects between you and the comet.
Now set your camera to RAW. You're shooting during a time of day (night) when cameras have a difficult time picking out details, and you want the best opportunity to grab as much information as you can out of the night sky. RAW is going to do a better job at this than JPG.
Next, turn your camera's ISO up to at least 800. If your camera can take noise-free photos at higher ISOs, turn it up even more. You want to avoid capturing motion in the night sky (star trails will distract from your subject, and a motion-blurred subject will do the same thing) so shoot at higher shutter speeds if possible.
Next, put your camera in manual mode. And I mean manual everything, including focus. Did I mention that comets are fuzzy-looking? That means you can't even rely on your own eyes to focus on them - instead focus on another bright object in the night sky, then recompose.
Now set your camera to mirror lock-up, which will work with your cable/remote release to minimize camera shake.
Taking the shot
Now if you've done astrophotography before, you know that the longer your lens, the more the movement of night sky objects will be magnified, and the shorter your exposure will need to be in order to avoid light streaks in your photograph. If you're using a 100mm lens, for example, you can really only use a 5 to 6 second long exposure before those stars turn into streaks. With a 400mm lens, your exposure is going to be more like 1.5 seconds. So unless you have a motor-driven tracking system for your camera (a piece of equipment that locks onto your celestial subject and keeps it in the same position in the frame for the duration of the exposure), you're going to be relying on that high ISO and a reasonably wide aperture (f/4 should be about right) to get a clear shot.
Bracket your shots - take one at the recommended exposure, one below and one above. This will give you a range of images to choose from, which is important because your camera's meter is much less accurate during night time conditions.
Starry Night Lovejoy by Flickr user lrargerich
Don't just shoot the comet--back off a little and get some shots of the comet and your surroundings, too. Include the horizon, or another star-gazer, or anything else that might add some context to the image. Take lots of shots and bring a couple of lenses. You'll want a lot of images to choose from because some are going to work while others don't, and let's face it, you're not going to want to get up at that time of night twice.
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