How to photograph the Andromeda Galaxy
This was my first attempt at capturing the Andromeda Galaxy from my backyard. In this blog post, I’ll show you how I did it and will explain every step of the way so you can try it yourself!
I’m very new to astrophotography, but I quickly noticed that if you do not get discouraged after a few failed attempts, that astrophotography is a very rewarding hobby!
Equipment
You might expect that you first need to buy an expensive telescope, a high-end camera, and a mount that counteracts the rotation of the earth. But that is not true! The image I took was made with a standard mirrorless camera (DLSR’s work!), a cheap refurbished telephoto lens, and a free tripod that someone was throwing out! So, all in all, you’ll need the following:
- A Camera (DSLR or Mirrorless)
- Telephoto Lens (a focal length of 300mm or less is preferred.
- Sturdy Tripod
Before buying everything from the list on Amazon, please check out second-hand gear. A lot of second-hand cameras are being sold for not a whole lot of money. Buying second-hand is especially a good idea if you don’t know if you would like astrophotography.
Now, if you have all the equipment needed, you can move on to the next step: preparation!
Preparation
There are a lot of things you want to keep in mind when attempting astrophotography, but there are three things that stand out:
- Dark Skies
- Clear Skies
- Camera Settings
Dark Skies
Now you might think: “Dark Skies? That is obvious, of course, I can only see stars at night!” well, you are technically correct, but there is a lot more to it. Actual “Dark skies” are getting increasingly rare because of light pollution. Especially if you live in Europe, light pollution is a big issue because it is so densely populated.
Dark Skies are defined on the “Bortle Scale.” The Bortle scale measures the quality (brightness) of the night sky for a particular location. Ranging from 1 to 9, with 1 being an excellent dark sky site and 9 being an inner city sky, with lots of bright lights. To find out what “Class” sky you have in your backyard, you can use a site like www.lightpollutionmap.info. You can also use this map to look for places where you have a better chance of seeing “true dark skies”. For the Andromeda Galaxy, you’ll need a Bortle class of 5 or lower for a good result.
Clear Skies
Because astrophotography needs a lot of preparation, it is annoying to have your night ruined by clouds. Because astrophotography is not as simple as taking a single picture, you’ll need to make sure that you have a clear night. The website I like to use to check is clearoutside.com. This will show you cloud predictions for the upcoming week.
Do keep in mind, however, that these are only predictions and can change day to day and hour to hour.
Camera Settings
To capture the Andromeda galaxy, you can’t just take a picture on “Auto” mode. You’ll need to use either Bulb or Manual mode. For my picture, I used manual mode.
ISO
Setting ISO is the tricky part. You’ll need a high enough ISO to capture the Andromeda Galaxy, but not too high to prevent noise in your photo. Because my lens has an aperture of f/5.6 at 200mm, I needed to increase the ISO to see the Galaxy. But a good starting point would be 800 ISO, and make minor adjustments until you are happy with your result.
Shutter Time
The shutter speed depends heavily on the lens and tripod used to make the photo. If you use a tracking mount, you can select the slowest shutter speed your camera allows. But if you are like me and only have a regular tripod, you need to use the NPF formula to calculate the maximum exposure time. I recommend this shutter speed calculator.
Aperture
You need to use the lowest aperture available on the lens you have. In my case, that was f/5.6.
Photographing the Andromeda Galaxy
Now you have a dark, clear sky, and your camera settings are figured out. Now you’ll need to make sure you can capture the Andromeda Galaxy. In the following chapters, I’ll explain the steps to successfully capture the Andromeda Galaxy.
Focussing the camera
In astrophotography, you can’t use the autofocus of your camera. Your camera only sees a black background with some white spots here and there. Luckily there are multiple ways of focussing your camera using the manual focus!
Manually
Point your camera towards a bright star. Any bright star will work. Rotate the focus ring towards the infinity symbol. At this point, you should see a white spot on your screen. Adjust the focus so that the white spot is as small as possible. This is very finicky, but this has to be correct, or all of your pictures will blurry.
Using a Bahtinov Mask
An easier way of getting focused is using a Bahtinov mask. This will make focusing way faster and easier. The only problem is obtaining one that fits your lens. If you or anyone you know has a 3d printer, you can easily print one and put it over your lens.
All the stars will appear with long streaks. If you have successfully focussed your lens, the stars will look like this:
Finding the Andromeda galaxy
Finding the Andromeda Galaxy takes effort, but it gets easier if you have tried it multiple times.
First, install Stellarium on your mobile phone. This will help point you in the right direction. You can search for M31 in the search bar, and it will automatically show you where the Andromeda galaxy is. If you point your phone to the sky, the app will automatically use its GPS function to let you know if you are looking in the right direction. If you place your phone on top of the camera, you can point your camera in the right direction.
Now before you take a lot of pictures, please make a test exposure. Set the camera delay to 2 seconds and take a picture. It should look something like this:
Now this picture alone does not say much. It is mostly just darkness. You still can’t know if you are looking in the right direction. That is why I use nova.astrometry.net to see if I am looking at the right thing. You can upload the test expose there, and it will annotate the stars in the picture like this:
The big circle is annotated with NGC 224 / Andromeda Galaxy / M31. That is the target we want! Make sure it is in the middle, and you can begin your exposures!
Intervalometer
Now you can stand next to your camera for an hour+, but that is not necessary; you can either use the internal intervalometer or plug in an external one. For this guide, I simply used the internal intervalometer in my camera. I set the intervalometer to take about 150 pictures of 2 seconds each. This is not enough photos for the final result, but after those 150 pictures, you’ll need to adjust your camera position to keep the Andromeda galaxy in the middle of the frame.
Make sure you have (at a minimum) an hour’s worth of exposure. For me, that totaled to about 900(!) pictures.
Taking Calibration Frames
Taking Calibration frames is highly recommended. This will make sure that your final result will look as clean as possible. You can find a good guide on taking calibration frames on www.macobservatory.com.
Stacking the Andromeda Galaxy
We will need to use a stacking program to stack all the images. For this tutorial, we will use DeepSkyStacker.
Since it is too much information to explain in a blog post, you can use this tutorial to stack your images:
Once you are done stacking, it may not look like you expect it to, but that is ok! We are moving over to the next step, editing the picture!
Editing the Andromeda Galaxy
Now the image you got out of DeepSkyStacker looks very dark. So we will need to do something about that, for that we need another piece of software named Siril. Once you’ve downloaded it, do the following:
Final Result
After more than an hour outside in the middle of the night, stacking and processing, I finally got the result I wanted: The Andromeda Galaxy!
More astrophotography
If you like this post and want to see what else I’ve photographed, please check out my astrophotography gallery:
