Astrophotography Presentation by Alex Cherney

Loch Ard Gorge

© Alex Cherney

Wow... I couldn't think of another first word to write. Right from the opening slide of Alex Cherney's astrophotography presentation I was in awe. You can see the opening image in this article.

It's pretty amazing to know Alex has only been indulging his interest in Astronomy since 2007 and now describes himself as an amateur astronomer, all the while making some extraordinary astrophotography images of the night sky.

The photo above was taken on the Great Ocean Road at Loch Ard Gorge and amazingly the only artificial light in the image is way off to the right, the faint orange glow of the lights from Warrnambool, the rest of the image is lit with starlight.

Alex retold the story of his daughter's request, at 4 years old, to help him find Aliens for school. This lead him to the Mornington Peninsula Astronomical Society and with his first look through the the telescope, while not finding aliens, he found a passion for the stars. Very soon after he bought his first telescope, which was quickly replaced by a bigger one, then a bigger one, then a bigger one over the last few years. He has, currently, settled on his latest... a 22 inch mirror-based telescope that has let him see objects up to 1.5 billion light years away.

My mind is blown, my hunger for looking closer at the stars is whetted, and I'm sure most of the audience felt the same.

Alex next had us stunned by showing us more photos taken with his Nikon D700 and explaining that although these images looked like they have been coloured, they in fact haven't. The colours captured are natural and it is the limitation of human night vision that prevents us from seeing the true colours of the stars, colours that our camera's can capture.

The photography lead to the making of short time lapse videos, one of which, Ocean Sky, shown below, saw Alex awarded overall winner prize at STARMUS astrophotography competition.

As a winner, Alex was invited to the STARMUS festival, a week on Canary Islands in 2011 where he was privileged to hang out and rub shoulders with some of the most famous people in the field; including Neil Armstrong, Buzz Aldrin, Brian May, Richard Dawkins, Bill Anders, Kathryn Gray (the youngest person ever to have discovered a supernova) and many other people I couldn't write fast enough to note. Apart from meeting these liminaries, Alex was also awarded with an hour's viewing time using the Gran Telescopio Canaria, the world's largest optical telescope.

While the time lapse that won Alex this prestigious award was only 2:41 seconds in length, Ocean Sky, was one and a half years in the making. An amazing and beautiful feast for the eyes and the ears.

Make Your Own

After enthralling us with his wonderful imagery, Alex laid forth the challenge... we too can make images like his; and we could do it with our own digital SLRs and kit lenses.

Open and sharing, Alex went on to detail the steps needed to make stills, composites (for star trails) and time lapses of the night sky. He discussed how to find great locations and how often the foreground was as important as the stars beyond.

Items needed

To do this, Alex advises you need the following items:

• Warm clothing.
• A sturdy tripod
• DSLR with live view or a mirrorless camera
• A wide angle lens (18mm or less)
• A remote trigger and/or intervalometer (for sequences)
• A torch or headlamp (cause it's night and you need to be able to see what you're doing)

Camera settings

• Manual exposure
• Manual focus
• Manual white balance, set to around 4,300K (edit: Alex has also advised you can use the Sunny white balance setting if you don't have a Kelvin scale on your camera)
• ISO 3200 (at 15 seconds) or 1600 (at 30 seconds) where the moon is less than 15%
• Widest possible lens setting
• Largest possible aperture

Steps

1. Set to manual focus
2. Set focus to infinity mark (or furthest if you don't have infinity)
3. Center camera on a bright star
4. Turn on live view
5. Magnify live view
6. Turn the focusing ring until the smallest star image is achieved, paying attention to the smaller, dimmer stars
7. Set exposure time.

Exposure time

This one is tricky, there's a rule (more a guide) to make sure you don't end up with star trails and to keep your image as crisp as possible. It's also based on the supposition you're shooting with an aperture around f4.

The rule is the maximum exposure time = 600 / effective focal length.

Meaning on a Canon 500D with a crop factor of 1.6 the equation would be 600/(15x1.6) = approx 25 seconds.

Other tips

Alex was a wealth of knowledge. Members of the club will benefit from a PDF of Alex's presentation which will hopefully correct any little mistakes I made during note taking. But here's a couple more general rules Alex shared.

• To shoot the sky in and around Melbourne. Avoid light polution. Travel about 150km from the metropolitan edge or travel south and shoot over the ocean (Mornington Peninsula, Great Ocean Road).
• Aways shoot in RAW. RAW produces unaltered data in 12-14 bits rather than the 8 bits of a JPG image. Basically meaing you have more information to play with.
• Don't use noise reduction unless you're taking a long exposure (in minutes) instead use noise reduction of your editing program or something like Noise Ninja or Neat Image.
• Use a series of shorter exposures, stacked, to make star trails rather than a single super-long exposure. Super long exposures will show up your hot pixels more and they will be harder to deal with in editing.
• Use free software like startrails.de to stack your images to make star trails.
• Make sure you have consecutive numbering if you're going to make a time lapse.
• Find free music to accompany your time lapse at Jamendo or The Audio Archive be aware of the rules of Creative Commons Licensing when using this audio (or any creative common's properties).

Where to find more information about Alex Cherney

• Visit Alex's site Terrastro
• Watch Alex's time lapses on Vimeo.

Alex Cherney would also like people to be more away of the efforts to improve the night sky for all. An amazing number of people from Europe and the big cities in the US have never seen stars in the night sky. The large amount of light pollution has rendered the stars invisible to the naked eye.

To find out more about these efforts visit The World at Night (TWAN)

We're grateful to Alex for sharing his time and knowledge with us at the Williamstown Camera Club. It was a fantastic presentation we all enjoyed.