Aurora

by Alan Godfrey February. 03, 2021 230 views

I've always loved looking up at the stars. As a child, on holiday on a summer's evening I would spend hours just staring up at them - trying to comprehend the scale of them and the distances in between.

Astrophotography is a long-term goal of mine. I've not yet taken a photograph of the night's sky that I am happy with, and would like to be able to capture some of the beauty and wonder of what I see in future, but to date I have not had the right combination of equipment, knowledge, time, and luck required.

I can work on the first two, and will have to just wait and see for the other two!

My one experience to date was a fabulous opportunity in 2018 to photograph the Aurora Borealis in Iceland.

Photography was only a recent hobby, and this was a family holiday. I had some decent equipment, and spent some time reading up optimistically in advance about techniques and settings, but as they say - no plan survives first contact with the enemy - and while the photos that I came away with still bring me pleasure, I learned a lot from the experience that I would like the opportunity to improve on next time.

Aurora Borealis, Reykjavik, Iceland, October 2018

Aurora Borealis, Reykjavik, Iceland, October 2018

More than anything, we were just lucky to see it - and I didn't want to be fussing over my camera settings too much to not experience it.

The weather forecast for the week had been for constant cloud cover, and we'd resigned ourselves to not being able to see it. On the third night, suddenly, the forecast suggested a brief gap in the clouds aligned to a strong aurora. With a fast-asleep four year-old wrapped up in bundles of clothes in the back of our hire car, we raced down to the lighthouse just outside of Reykjavik - not wanting to risk driving too far out of the city in the dark on unfamiliar roads for a fleeting chance.

We waited unsuccessfully for just short of an hour, and were about to give up when the smallest of gaps in the clouds appeared and the green glow could be seen through. It was gone almost as soon as it came - certainly too short to take any decent photographs - but we were still overjoyed at even the briefest of glimpses.

Aurora Borealis, Reykjavik, Iceland, October 2018

Aurora Borealis, Reykjavik, Iceland, October 2018

As if often the case, we returned to the flat we were staying in telling ourselves that was enough... that we wouldn't go out chasing a fleeting glimpse again, that we were satisfied and would focus on getting good night's sleeps and enjoying the restful vacation now... only for the forecast two days later to blow those intentions out of the water. Now the forecast was suddenly for a strong aurora and a completely clear night. Who could pass that up?

Aurora Borealis, Reykjavik, Iceland, October 2018

Aurora Borealis, Reykjavik, Iceland, October 2018

We headed out again of course. The sky was so clear and the aurora so strong that we could see it from the moment we left our flat in central Reykjavik.

We decided to head back to the lighthouse again - a known commodity, or so we thought. By the time we arrived - this time - so had everyone else. Unlike our first viewing, where we were almost alone - clearly everyone else had seen the same information we had and there was almost nowhere to park!

With the aurora already weakening, we decided that it wasn't worth trying to find an alternative spot; so parked where we could a little way from the lighthouse and walked down. Sadly this meant that, where the first time we had been able to let our daughter sleep soundly and warmly in the back of the car while we waited, she had to be woken and carried with us. (It does mean that she got to see it, but - in her words - "it's beautiful daddy, but it's cold - can we go home now?")

I'd brought a tripod with me this time, and was determined to get it set up and attempt to get some decent images; but had to work fast.

The three images in this post are my favourites. As usual, I wanted to use this write up to think more critically about them - and see what I can learn for next time.

Equipment

First and foremost, the tripod was essential. Seems obvious, but worth stating. I took a few quick shots handheld when I first arrived, in case it vanished before I could be set up - but there was no way those shots would be keepers.

These images were taken with a full-frame Canon 6D, with EF 24-105mm f/4L lens attached. The Canon 6D is notorious for good low light performance, and being able to keep noise low at reasonably high ISO - which was ideal for this situation.

The lens choice was OK. A faster wide-angle prime would have given more flexibility to keep ISO low, but might have limited composition; a faster wide-angle zoom would have been ideal... minor points really.

Settings

As usual, settings is where I have the most constructive criticism for myself.

Across the three photos, all were taken at 24mm with the following settings:

  1. 30 sec at f/4.0, ISO 200
  2. 0.6 sec at f/4.0, ISO 6400
  3. 20 sec at f/4.0, ISO 800

Two things jump out:

  • You can see from the second image that a ribbon aurora, rather than just a flat glow, was visible. This isn't apparent from images 1 and 3... because I've exposed these for too long. 30 seconds and 20 seconds respectively.
  • Conversely, while I've captured the ribbon in the second image, ISO 6400 alongside needing to boost exposure almost 3 stops in post-processing, has resulted in a very noisy image; even with noise reduction applied.

Looking quickly online suggests 15 seconds maximum for a slow moving aurora, and closer to 10, or even faster, for a fast moving one. This was a fast moving aurora, so exposing longer allowed me to create less noisy images, but with the aurora blurred to a green glow across the sky, and exposing too quickly pushed the ISO too high to get a decent image.

If I've calculated correctly, if I had used ISO 1600 for each image, the same exposure could have been achieved with a shutter speed in the 5 - 10 seconds range, which would have been what I was after.

The Canon 6D could have coped with ISO 1600, although with post-processing pushing the exposure an additional 3 stops making it more like ISO 6400, that might have been closer to its limit. At which point, the only solution becomes a faster lens. F/2 or faster would appear to be the sweet spot ...

Hindsight

More than anything, being in the right place, at the right time - and getting a bit of luck - is what matters. I'd rather have blurry images that I can critique than none at all!

Experience matters... this was a first attempt, and I've not even begun to critique my composition, or the wider image aesthetic, but at least next time if I can learn from this experience and get the settings nailed quickly, I can move on to working on the rest!

Just need to be able to travel again now ...

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John Durham 2 months ago

I really appreciate the patience and dedication it takes to get these images. Being in the right place at the right time.. yeah, but being willing to wait and endure - that's special, my friend. A fantastic job.

2 months ago Edited
Benny Law 2 months, 1 week ago

I always enjoy the depth and details of your posts. Thanks for taking the time to share your experience, lessons, and insight.

2 months, 1 week ago Edited
Alan Godfrey Replied to Benny Law 2 months, 1 week ago

Thank you for those kind words Benny. I appreciate it!

2 months, 1 week ago Edited
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