Shooting Stars: An Introduction to Astro Photography
July 12, 2018
So, I hear you want to shoot the milky way but you don’t know where to start. This article will teach you the things you need to know to get out there and start capturing the milky way like a pro.
The first and biggest step to any successful milky way shoot is planning. Planning can be broken down into a few simple steps.
Planning
The moon
Now you might be thinking...Hang on Robbie, why do I need to know where the moon is? I want to shoot the stars, not shoot the moon! The reason we need to know the location of the moon is to avoid it. The moon adds a fantastic amount of light pollution that will limit the amount of stars you can see. The darker the sky you shoot in, the more visible the weak and distant stars will be.
The app I use to be able to track the moon is "Phases of the Moon” on android.
Location
Now we know a dark sky is needed to witness the sheer awesomeness of the milky way, we need to scout out a location that will allow us to find a place with minimal light pollution from city lights, street lights and so on. While this isn’t so critical, it will affect how well you see the galactic centre and how magnificent the milky way looks.
So find a place that is out of densely populated areas and has an interesting landscape if you can. I use the “Dark Sky Map” app to find locations that have a dark sky.
There is one more thing to note however, think about areas on the horizon that may affect that portion of the photo. For example, the image below was taken in the direction of a small city. This has produced a slight glow on the horizon. If that’s something you would like to avoid then you will need to take this into account when planning the location.
The Milky Way
Getting a great shot of the milky way starts with knowing when and where you will be able to see it in the sky. Unless you’re fortunate enough to live in a dark sky area and don’t need to plan a trip where you will need to drive 100+ kms to see it, you will need to know when and where to go, so you can plan the trip. I use the application “Star Walk 2” to achieve this. "Star walk 2" allows me to fast forward to a certain date and time so I can see a fairly accurate representation of what the sky will look like in an any given direction. This is a powerful free application but it has its flaws. The UI is a bit hard to work out for the first time user and the fast forwarding through time can be a bit tedious as it is gesture controlled. You will see what I mean when you start to use it.
This has been my not so secret weapon in my Astrophotography kit for about a year now.
The Weather
In the past I have been one to fret over if it’s going to be a perfectly clear night and would often put off going out to shoot if there was even a few clouds in the sky. I do check the forecast again from a weather app on my phone just to ensure it’s not going to pour rain on the night I plan to shoot. This is the last thing to look at - usually less than a week out from the shoot as the weather forecasting is historically not very accurate more that a couple days in the future.
I do have a backup plan for if clouds spoil my shoot. More on that later!
Gear
Now you have a location, the sky will be dark, the milky way will be in the sky and the weather is looking ok... You need to know what gear to take!
Like a lot of photography, the gear can play a big role in the quality of images you get. For the shoot featured in this post I shot on a Sony A7 Mark II, although any camera with an interchangeable lens mount will do the trick. Since the lenses used in the exercise will be most important factor we will need to be able to change them, hence an interchangeable lens camera such as a mirrorless or DSLR is the way to go.
The first lens I used is the New 14mm f/2.8mm Auto Focus lens from Samyang. While for Astrophotography we turn the auto focus off, If you do other kinds of photography you will probably want a lens that will auto focus. I used this lens for the landscape shots where I wanted to show the foreground and sky in the same shot.
For a tighter more sky focused shot I used the New Samyang 35mm f/1.4 Autofocus lens. This focal length makes the milky way look much nicer but it won’t allow for much of a landscape in the frame. So using foreground objects like trees and buildings will give your image perspective while still showing the milky way in all its glory can be a pleasing affect.
Make sure you take a sturdy tripod! On this shoot I took along my trusty MeFoto Globetrotter. Also extremely handy is a wireless remote trigger like the Hahnel Captur Timer Kit. This kit has a wireless remote that will work upto 100m away and has built in and easy to use time lapse functionality. This remote is very affordable, and it’s a great addition to any landscape photographer's kit. I also brought along a hat mounted flashlight so I can see what I’m doing in the dark whilst simultaneously being about to still operate the camera. I often needed two hands to re-orientate and reframe my camera on the tripod, so having a hat mounted light was very useful.
If you’re one to get creative you can bring along things like mini LED lights, glow sticks or other lights and play around with light painting. The sky is the limit (pun intended!) of what you can create when light painting!
For more gear recommendations check out Astrophotography Gear: A Beginner’s Guide.
Settings
Now the we have our gear planned we need to know what settings to have.
Your shutter speed will need to be long to allow enough light into the lens, however too long and we will get star trails! Because the earth spins, the stars will move in the sky. The more wide the focal length of the lens, the less noticeable this is. A good rule for calculating the appropriate shutter speed for your lens is the 500 rule. Divide 500 by your lens's “full frame equivalent” focal length. For example, for the Samyang 14mm f2.8 lens this was 500 / 14 = 35.71. I would round this down to 30 seconds to make sure the stars are nice and sharp. The slower the shutter speed, the sharper the stars will be... in theory! For all my astro shots featured here I used either 5000 or 6400 ISO and my aperture was as wide open as the lens would go.
Timelapse
Now, thats all well and good but what happens if it’s cloudy and you can’t get a decent view of the milky way?
Have a back up plan! My back up plan is to simply set up a time lapse. With time-lapses with clouds actually are somewhat a strength and they’re excellent to watch.
This is a time lapse I captured on my last astrophotography trip. It was the first night and it started off really cloudy. I figured, let’s make the most of this and set up a timelapse! I pulled out my trusty Hahnel Captur Timer Kit and waited for night fall. I had worked out that the moon would set at about 7pm and the galactic centre would be over the eastern horizon at about 9pm. I set up using Google maps as my compass and "Sky Walk 2" as my guide where the milky way will be. This can be a bit tricky because for something like this I had to rely on these apps to know where the milky way will be exactly, so I can set my composition ahead of time.
I calculated that to get 20 seconds of video footage I would need 480 single shots. I knew my shutter speed would need around 25 seconds to capture enough light in the scene. I decided to leave 5 seconds in between shots to round it out to 30 seconds and give my camera ample time to save the file and set for the next image. So, I’m taking 2 images a minute and I need 480 images. For a 24 frames per second video this gives me 4 hours of shooting time. Interestingly, the battery in the A7 Mark II lasted 478 shots before needing to be changed!
This leads me to the extra gear you will want for doing longer time lapses - I would definitely want to have a battery grip on my camera (especially the A7 Mark II or any other smaller mirrorless cameras).
I had a heavy bag to weigh my tripod down for my timelapse shoot as I did not want my tripod to move even the slightest during the 4 hours I was shooting! Bring headphones for music or podcasts too.. for 4 hours your camera will be working hard but you won’t be!
Because there are so many ways you can make the video out of the stills I will leave that up to you on how to do that. I simply batch edit the images in Lightroom and export them as JPG or TIFF files. Then I drag them all into Final Cut Pro X. They will all be default as 10 seconds per image on the timeline. I select them all with “Command A” and make a compound clip. I then hit "Command R" to retime the clip. I make the runtime 20 seconds as I know that’s how long it should be with 480 images. And boom! Export the video.
Final Thoughts
Well, there you have it folks - My entire process including gear list and shot settings for creating some beautiful astro images! Now you know how it all works - get out there and give it a go! We'd love to see what you create, and if you have any questions feel free to get in touch!
Images, Video & Words by Robert Bouchardt