Nightscapes, What, When, How.

February 28, 2019  •  Leave a Comment

IMG_20180720_0004IMG_20180720_0004 June 1984 handguided 6 minutes ASA1600

 

From March to November an army of Photographers can be found wandering around in the dark trying to catch something that most people have never seen, the Milky Way. The changes in camera technology introduced with Nikon D3 allowed easily the capture of the night sky in all its glory with the landscape. Until this time the best we could manage was either a guided shot of the Milky Way itself or a start rail with the landscape.

 

I fell into Astronomy first at the age of 8 and Photography at 13. It was natural for me to want to combine the two and I became quite adept at first with taking star trails. Later as my scope became an equatorial, mount which could track the stars, I started to take shots of the Milky Way. I was almost alone in this endeavour. Yes there were other people shooting Deep Sky objects but it was rare to see the central bulge of the Milky Way captured. The film ratings in ASA were not good enough yet to capture true Nightscapes and I must admit I didn't try. If only we could go back in time and give it a try?

IMG_20180720_0005IMG_20180720_0005 Halleys Comet April 1986 handguided 6 minutes ASA1000

 

Eventually the thrill of capturing the Milky Way gave way to visual observing with larger and larger telescopes and the camera was left to shoot only daylight landscapes. This all happened between 1983 and 1990. My bias to visual observing became so strong that many people in the astronomical community whom I meet in the 90's still remark about me shoot the night sky.

 

I purchased my D3s in early 2010 and the reports of its Low light performance didn't do the camera justice. I had just gotten the shooting gig at Harrigan’s and had been shooting Weddings for about 5 years. I decided to purchase the D3s for those jobs but soon thought about trying the night sky. I had tried with my D300 I bought in 2007 but it ran into trouble at about ISO800 with noise. With the D3s I was able to shoot at ISO1600 cleanly and even up to 6400 with some acceptable noise. The trouble was at that time I didn’t have a fast wide lens. The 24-70mm f2.8 lens was good for aperture but I found the start trailing to occur before the landscape had a real chance to record. At the start I had to calculate the exposure time by trial and error, not a problem with digital, take a shot, have a look, and shoot again. The world of Nightscape shots really opened up for me in 2011 when I purchased my first 14mm f2.8 lens. Suddenly I was getting the amount of light I needed to capture the sky properly and an exposure time that allowed me to light paint the landscape. I experimented with different lenses and apertures and discovered the joy of narrowing the field of view and adjusting the exposure time down to suite. By late 2011 a small community of Nightscapes had sprung up and the rule of 600 was passed around. The rule of 600 worked in the early days due to the resolution of the sensors. Also in 2012 a number of affordable consumer DSLR cameras came out with a low light performance good enough to really start to shoot nightscapes. The community grew as cameras that could capture the Milky Way became more affordable. I already knew many people into astronomy both in Australia and abroad due to my visual observing and I was lucky enough to build friendships with some of the big names in Astrophotography. I found by 2014 that I was spending more time at my camera under the night sky than at the eyepiece of my telescope. I trailed a D4 when it came out and found it performed the same as the D3s so I didn’t upgrade the camera so I waited till the D5 was released.

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A shot from 2011 near barrington tops.

 

So what does this army of Photographers do? That’s quite hard to say really but it would seem to me that they start by driving long miles to get to a dark sky, spoil their night vision by using an app to locate the Milky Way, and attempt to shoot it. Unfortunately Nightscapes are initially a lot harder to shoot than people think. What ISO do I use? How do I focus? Which Lens should I use? Why do the photos I see on Social Media look so much better than mine? How do I get the foreground sharp when I’m focused on the stars? These are just a few questions that need to be answered when you start to learn to shoot at night.

 

There are a lot of misconceptions about ISO and how to use it effectively. It also doesn’t help that camera manufacturers create some sensors that are ISO invariant and some that are not but that’s a story for another time. When you select an ISO in the camera you are selecting the sensitivity of the sensor to light. Unfortunately Nightscapes are not “light”. For any given ISO setting there is a minimum Noise level. When you take a nightscape image you are recording the image as a signal. It’s the ratio of Signal verses noise that determines how noisy your image will ultimately be. The more signal I can collect during the exposure the better the image will be. For Nightscapes you can’t just lengthen the exposure as you don’t want stars to trail. This is why it is recommended to have an f2.8 or faster lens.  I shoot with a 20mm f1.4 lens, this lens collects 4 times as much light as an f2.8 equivalent. Put another way if you shot the Milky Way with a 20mm f2.8 lens for 20 seconds and then another for 80 seconds and compared the two you would notice that while the stars did trail the landscape is recorded with much more detail, even to the point of not needing much or any light painting at all. The same shot taken by my camera at the same settings just the f.14 lens difference will look the same as your 80 second exposure just with no star trails. Much more signal without the need to “push” the image in Photoshop and therefore much less noise.

 

Focusing can be a challenge but there are a few tricks you can employ to make sure you get it right. The markings on your lens are rarely accurate so putting the lens to infinity won’t work, but it’s a good place to start. All cameras from 2012 have liveview as a function and it’s via liveview that you can focus you camera. Point the camera toward the night sky in the direction of some bright stars. Turn on the liveview setting and use the + to zoom into the image of the back screen. Make sure your aperture is as open as it can be. Once you find a star adjust the focus until the star is at its smallest. It’s even better if you notice some faint stars pop into visibility at this point as this can only happen if the stars are in focus. So what happens if you can’t see the stars on the back of the camera? Well there is a cheat you can use. Each lens has a distance at which infinite focus is reached and that is dependent of the focal length of the lens and the aperture you happen to be shooting at. For instance the 14mm Samyang reached infinite focus at about 3 meters away at f2.8. The Tokina 11-16 and 11-20mm lenses reach infinite focus at about 5 metres and my 20mm Sigma Art does it at approximately 10 metres. If you know the infinite focus distance for your lens (take the crop factor into account) then you know where to place your torch which should then be visible in your Liveview. The torch can also help you compose your shot especially if you are including a tree, house or anything interesting. Also if you make the main landscape focus further than your infinite focus the foreground and sky will all be in focus.

 

There are many lenses on the market and each is usually make for a purpose. To my knowledge no manufacturer creates a lens specifically for Astrophotography. I use a variety of lenses ranging from 14mm f2.8 Samyang, 20mm f1.4 Sigma Art, 35mm f1.4 Sigma Art, 50mm f1.4 Nikon, 85mm f1.8 Nikon and a 135mm f1.8 Sigma Art. I have even used my 70-200mm f2.8 on occasion. Each lens has a different look and need a different exposure time to get the image right. I use the rule of 500 to calculate the exposure time. The rule of 500 states that the focal length of the lens divided into 500 gives you the exposure time. Also when you calculate the exposure time you need to take the Crop factor into consideration. The rule of 500 will only give a rough estimate of the exposure time, it’s long and complicated but suffice to say 2 things determine the rules accuracy. First the closer you shoot to celestial pole in your hemisphere the better the rule of 500 works. And the larger the MP of your camera the more trailing you will see. (Beware you D850 users). As you can see by this a 14mm lens allows for a longer exposure time than a 20mm. As I mentioned above though the larger aperture works better at recording the image data. The difference between the 14mm f2.8 and a 20mm f1.4 is effectively just over 1 stop due to the longer exposure time. The wider the lens the better but also the wider the aperture. That’s why the Samyang 14mm f2.8 is the most popular lens for Astro. That also why I have a Nikon and a Canon version of the lens for people to borrow at my Astro workshops.

 

Social media is a great platform for people to gain ideas and to mix with people who have similar interests. Most of the Astro images posted on Instagram and Facebook have been processed.  I understand there is a group of people who believe that photography in its purest form does not need post processing. Get it right in camera is the war cry for this movement and while I do agree that you should get your images as close as possible in camera I also know that the way a digital camera works is not like the human eye. You must, I will say it again, you must post process the image. Nightscape images even more so. Firstly you have an underexposed image, secondly the colour balance will be way off as the camera can’t get a good WB unless you set it yourself. Even then it will need adjusting. Post processing your images can a bit like art if you let it. It’s your decision as to how much processing you wish to do. As I mentioned earlier in the post I started photography at 13 and I learnt how to work a darkroom. That’s where most of the terms and tools in Photoshop came from. A contact print made from one of my negatives would look completely different to the final print I showed people. Learn to love to post process your images but also learn when to call it quits.

 

The Milky Way becomes visible in the morning sky at the end of January and early February. By the beginning of March the Centre of the Galaxy is fully risen an hour before dawn.  In April you can start to shoot about midnight and by June the Milky Way in all its majesty is visible from Dusk till Dawn. (Just don’t let the vampires get you). By August its overhead and a magnificent slight if difficult to capture in the early evening but is hanging on its side near the horizon by dawn. By late October and early November the Milky Way lies now on the western horizon setting on its side almost parallel to the ground and by the end of November it’s gone again for another year. The constellations of Scorpio and Sagittarius lie on the southern ecliptic this means that they rise in the east, so look for a good eastern horizon. The same goes for the setting Milky Way, look for a few nice foregrounds with a good westerly view. The Galactic centre is not the only thing worth shooting though. Just because its set doesn’t mean you have nothing to shoot. Try capturing the Magellanic Clouds, Satellite galaxies of the Milky Way. The Orion, Taurus and Monoceros regions and the area around the Southern Cross with Eta Carina.

 

While for many the pursuit of the Milky Way is a new and exciting phase of their photography career it can also be a rewarding one. It can take you to new places, challenge your skills, introduce you to new people and maybe educate you on the Universe around you. Astronomy is an amazing subject just like Photography and for me combining the 2 has been something I have been doing for almost 40 years. No one knows everything and I am still learning new techniques and tricks. If you would like to learn from someone with nearly 40 years’ experience with photography who is also an internationally known and awarded astronomer please send me a message.

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