A revolution is afoot in visual astronomy. More and more often, we’re seeing live video capture replacing the old ‘Mk-1 eyeball, plus eyepiece’ mode to view the sky. And while an argument can be made for the old hands-on (or eyes-on) approach to viewing, video – whether via camera of electronic eyepiece – is a great way to share and chronicle the sky.
Here’s a short slo mo video of the International Space Station transiting the full lunar disk at 17,500 mph from Los Angeles based astrophotographer Jarred Donkersley of darkskymatters.com.
The use of ‘video’ in the modern digital era has reality merged into what could be better termed as ‘high-speed (that is, high frame rate) astrophotography’.
‘Lucky imaging’ or image stacking is a method that goes back about two decades now. This method is especially suited for planetary photography, where fleeting moments of ‘good seeing’ can briefly pop out through the shimmering of the atmosphere. We recently wrote about this method for AstroGearToday in How to Image Planets.
The other method is true video imaging, for a live view of the sky. For years, we simply used a JVC digital camera or a DSLR mounted afocally to shoot video through the telescope. Our new preferred camera for video is a ZWO ASI 120-MC S camera, running directly to the laptop. This is a fast frame-rate, versatile color imager with a 1.2 megapixel sensor. The chief drawback, however, is the narrower field of view for focusing an acquisition about 10 inches across, a third the size of a full moon.
Orion, SVBONY, and Mallincam all offer true video imagers for views at the telescope or through a secondary screen (usually a laptop or tablet) running from a few $100, to over a $1,000 USD.
Early video astronomers simply modified security and starlight low-light cameras for astronomy. Some newer telescopes, such as Unistellar’s eVscope, feature an ‘eyepiece’ with an electronic sensor instead of the traditional lens and optical train, providing a view through a turret on the side of the telescope.
Using Video for Occultations
Though many astronomical events happen over timescales greater than a human life span, several spectacular events occur over short periods, and are ideal for video astrophotography. The sun can change from one hour to the next, and I frequently shoot video both in hydrogen-alpha and visible light if the sun is active. Likewise, lunar and solar eclipses both lend themselves to video astrophotography. But one of my favorite events to capture are lunar occultations of stars and planets, and occultations of stars by asteroids.
Lunar occultations are tricky, as you have to balance the focus and contrast of the bright Moon versus the relatively faint planet of star. I like to run audio via shortwave WWV radio out of Fort Collins Colorado in the background, to get a precise time hack during the observation..
And, of course, running shared video is great for public outreach and live viewing with a large group.
Oldest example of video astronomy? Sputnik booster video from 1957:
An example of one of our own occultation videos:
Whatever the application, be sure to give video astronomy a try.