Astroterrestrial photography

This is a slightly longer post than normal, being made up of four individual posts.

Astroterrestrial photography

The three elements

8 April 2019

This photo of "the Emu" (the Indigenous name for the Milky Way in the area of the Southern Cross) was taken three years ago today. My octogenarian father had come up to Wyperfeld NP with me for a couple of days. I was after Jupiter as well as some birds. He wanted to see the place again and, I think, to spend some time with me, which I appreciated.

This is what I call an astroterrestrial photo. That is, it is a combination of astronomical and terrestrial imaging.

It's by no means perfect, but photos can be very evocative and I like the feeling this photo gives me. It helps me remember the evening. My father is sitting in a folding chair, with a few bits and pieces around him.

A large subject in this type of photo, like a tree or a lighthouse, gets a lonely quality, as though it's alone in the universe. In turn, having a subject does give the image something to draw the eye, as well as giving the sky some scale. I find subjectless photos a little unsatisfactory.

This type of photo has three elements:

1: Long exposure for the sky

I used a built-in feature of my DSLR to capture the stars. The exposure itself is 5 minutes, which on another camera would have resulted in trailing. The Pentax Astrotracer works pretty well, but as we will see, there are other ways of going about it.

2: Foreground and the background are both in focus

I relied on depth of field to give me focus on both sky and ground. This got me close, but you'll see that neither are sharp.

3: Light painting

I clumsily used a torch for this, but I found later that a mobile phone screen gives just the right softness of light.

The photo itself was taken using a non-orthogonal "fish-eye" lens, so it distorts the image. You can see this in the curve of the ground. It's also got a nasty green hue. This was because there was some airglow around on the night. I think I probably overexposed it as well. Again, I tried to correct it in Photoshop, and it's better than it was.

A single image from David Marriott

10 April 2019

David Marriott has taken an astroterrestrial photo of the Emu that puts mine in the shade. It's at Aries Tor at Ramshead Range in NSW in Early March 2019.

The subject is the yellow tent. As with other subjects, this confers a feeling of solitude (but not necessarily loneliness) onto whoever is in that tent. It also has an introspective quality, I think. It's funny how looking outwards can make you look inwards.

Remember the three elements I talked about the other day? David has taken different approaches to two of them.

The long exposure for the sky is not a long exposure after all. It's a single 30 second exposure, with a relatively high (6400) ISO. At 30 seconds with a wide angle lens, no tracking is required. The camera is just sitting on a tripod. Some Photoshop tweaks helped though.

To get the foreground and background in focus, David used the same approach as I did, which isn't surprising as it was a single image. Both sky and ground are in focus due to depth of field. David's 10mm lens is clearly great for this. He also told me he had to stumble around a bit in the dark to find the right position. Something close in the foreground would have been out of focus.

For light painting, David used a head torch as a light source. Looking back at my photo, David has taken a way more subtle approach and spread the light around more evenly. Mine looks harsh and crude by comparison.

In other aspects as well. this is a great photo. David's lens is orthogonal, meaning the image isn't wildly distorted like mine was. His processing has emphasised the Emu itself rather than the stars, so it's much clearer.

Thanks for allowing me to use your photo, David!

I really like the fact that David used a single exposure for this image. You don't have to do this, and separating the sky and the ground allows the photographer a lot more flexibility. That's normally a good thing, but some people can't restrain themselves, and occasionally we see cringe-worthy impossible images. 

But here's an example of how this was done well.

A multi-image composite from Padraic Koen

12 April 2019

Remember the three elements I was talking about above? Here's a photo that ticks all these boxes in different ways to what David and I did in the previous photos.

This is Padraic Koen's photo called "Before and After Sunset". It was taken from Newland Head in South Australia, looking across to Waitpinga Beach. 


The main difference between this image and the ones I've shown already is that it's made up of two separate exposures. In fact, it's two different cameras, set up in the same place two hours apart.

To get a long exposure for the sky, Padraic mounted his DSLR on a Vixen Polarie star tracker. This is essentially a light equatorial mount, and moves the camera to compensate for the Earth's rotation. This gave him the ability to take a 200 second exposure of the sky. Of course, the ground will suffer from motion blur.

Instead of doing anything to refocus the ground, Padraic took a photo before sunset. He used ArcSoft PhotoStudio (a Photoshop alternative) to take the nicely tracked sky from one photo and the sharply focused ground from the other photo and combine them. Having separate images gave Padraic the ability to perfectly balance the light between them. 

As to the light painting aspect? The setting Sun did the work for him. Using the Sun (or more often, the Moon) as a light source worked well, but because it is not controllable, sometimes having an artificial light source is easier.

Incidentally, this photo doesn't have an obvious subject (apart from Orion, I guess). The solitary feeling that would normally be conferred on the subject, instead falls on the viewer. In my opinion, this shows the difference between feeling solitary and feeling lonely, and to an introvert like me, this is no bad thing. This probably shows more about me than it does about the image, but isn't that what art is about?

Thanks for the photo, Padraic!

Masterclass from Brage Bærheim

15 April 2019

I had planned to finish this short series of wide field astroterrestrial photos at the third one, but shortly afterwards I came across this photo and just couldn't pass it up.

Brage is a friend of mine from Evenskjer near Narvik in Norway. The photo shows the Aurora Borealis above a mountain south of Longyearbyen on the island of Svalbard at about 78° north. It was shortly before midnight on the 9th of March.

Brage used a Nikon D3 DSLR with an orthogonal 50mm lens stopped down to f/2. The exposure was only 13 seconds, and in order to get it that short, he pushed the ISO to 2000. While 13 seconds isn't a particularly long exposure, star trails are just starting to form.

Because he used a single exposure, getting the foreground and the background in focus required a good depth of field. While Sarkofagen is distant, leaving the lens fully open at f/1.4 softened the focus too much.

There are two sources of artificial light in this photo. The first is provided by the street lights in Longyearbyen behind Brage. There is also a subtle magenta tinge provided by the aurora itself, which can be seen on the mountains in the background.

In processing the image, Brage adjusted the colour balance to correct for the colour from the street lights shining on the snow. He also increased the contrast by boosting whites and highlights as well as deepening the shadows and blacks. Finally he used Photoshop to sharpen the image slightly, and reduce the noise caused by the high ISO.

Brage tells me that it isn't a particularly strong aurora, but he particularly likes the way its shape mimicked the shape of the mountain at that moment.

If he were to take this shot again, Brage says he would try to shift position to get rid of the mountainside in the foreground. He thought it upset the balance of the composition. He would also shorten the exposure even more, and try to take multiple images of the sky to begin to make a stack in Photoshop.

Takk for det flotte bildet, Brage!