Credit: Wally Pacholka/Astropics.com
Watching a meteor shower is one of the simplest acts of observational astronomy, requiring nothing more than a clear dark sky, a working pair of eyeballs, and patience. The same is true for imaging meteor showers. If you’ve got a DSLR camera and a sturdy tripod, you can start imaging meteor showers tonight.
Meteors come from a vanishing point perspective in space known as a radiant, but individual meteors can appear anywhere in the sky. You’ll therefore want as wide a field of view as you can get away with, to optimize your chances of nabbing a random meteor in the frame. I like to shoot off at a 45-degree angle away from a shower’s radiant, to catch glowing meteor trails in profile.
The technique is very similar to shooting star-trails. Simply set the camera to manual (bulb) setting, focus to infinity, and shoot 30-second to 3-minute exposures of the sky. What’s handy with a DSLR is that you can shoot a series of test frames to review the current sky conditions and adjust accordingly: dark skies are always best. The darker the sky, the higher ISO settings, faster f/stop and longer exposures you can get away with. Noise reduction settings are also handy on modern DSLRs but be aware that some early cameras would actually erase stars (!) as unwanted noise.
You will also want to time-delay your shots to avoid shaking the camera at the beginning of the exposure. In the days of film photography, this was done by using the ‘hat-trick’ method of covering up the front of the lens at the beginning of the shot or using a hand cable release; today, most cameras can be operated using small remote control.
Automating the Process
One of the handiest upgrades for imaging meteor showers is an intervalometer. This attachment allows you to program a series of shots. After it’s set, you can simply lay back and enjoy the meteor shower while the camera shoots the sky. Be aware, though, that the camera needs to cycle and process each time between shots, increasing the exposure time. Make sure the delay intervals are adequate, or the intervalometer will start skipping shots.
Another great upgrade add-on is a sky-tracker. These trackers range from the sophisticated computerized ones currently on the market, to windup mechanical trackers, to simple ‘barn-door trackers’ that you can make out of loose hardware and a large strap-hinge (commonly found on barn-doors) for about $10.
Dealing with Dew
Finally, be vigilant against dew forming on your camera lens in the field. You won’t want to wipe dew or frost off (it can scratch the glass). If it’s an especially damp night, wrapping a foam hood around the lens can extend your session; if you have a power source available, a hair dryer at low power can also keep your lens dew-free. Also, keep a spare set of fully charged camera batteries handy, preferably in a warm coat pocket: cold morning temperatures and long exposures can drain camera batteries in a hurry.
Early morning hours are the best for seeing meteors. This is because your local observing site is rotated forward headlong into the path of the Earth around the Sun past local midnight, meeting an oncoming meteor stream head on, like snowflakes in a snowstorm caught in your car’s headlights. Some meteor showers, such as the Leonids that peak every 33 years, can actually produce this effect in real time. Annual bests for meteor showers include the August Perseids and, in recent years, the December Geminids. Watch the International Meteor Observer’s website for real-time data on what observers are seeing from meteor activity worldwide.
Also, be sure to carefully review all images on the big screen before deleting them to catch meteors you didn’t see on the camera.
Good luck, clear skies, and good meteor hunting.
Links/resources:
- The International Meteor Organization webpage:
- I describe meteor observing and how to make a $10 barndoor tracker in my first book, “The Universe Today Ultimate Guide to Viewing the Cosmos: Everything You Need to Know to Become an Amateur Astronomer.”
