Have you ever looked up at the night sky and wished you knew how to photograph what you saw? In this article, we’ll look to answer the how, what, where, and why of astrophotography for beginners. My goal for this article is to help you be confident during your first outing to photograph the night sky. 

Note, this article is intended as a starting point. There are plenty of other skills and techniques you can use down the road. For now, we are going to look at the basics.

WHAT IS ASTROPHOTOGRAPHY

Astrophotography is defined as the photographing of celestial objects and phenomena

Dictionary.com

In short, it is the term used for any photograph of the night sky. Technically photographing the sun would count, but that’s not a great idea. Unless it is an eclipse and you have special equipment. But I digress…

Astrophotography, or night sky photography as I will focus on in this article, requires a few more techniques to your photography toolbox. Because you are working in lower light situations, you’ll be shooting in manual mode and focusing manually. Both things can seem daunting, but with some help, you’ll be capturing the night sky in no time.

WHY ASTROPHOTOGRAPHY

Why would you want to photograph the night sky? For me, the answers are numerous but boil down to a few silly responses. 

1. Because it allows me to photograph longer during a single day.
2. Because until only a few years ago you needed specialized (ie – EXPENSIVE) equipment. Now you can create great images on a budget.
3. Astrophotography is fun and challenging.
4. I find it gives me a fuller appreciation for the night and dark skies.
5. It’s a different way to view the landscapes with which we are all familiar.

WHERE CAN YOU PHOTOGRAPH THE NIGHT SKY

This is where things start to get tricky. Have you ever been to a city at night and looked up? Were you able to see stars? The answer is either very few or none at all. The moon is usually the main celestial object you can see amid the light pollution. Therefore, you’ll need to find someplace dark enough to see the parts of the night sky you’re after.

What are your options? Well, you could just start driving away from the lights that keep the night at bay. However, that’s not the most efficient approach. Let’s take a look at some better options for finding dark skies near you. 

TOOLS FOR FINDING DARK SKIES

So, if you can’t really see the Galactic Center in a city, where can you go? Fortunately for aspiring astrophotographers and those who just like stargazing, there are plenty of good resources to help you find a dark sky.

ONLINE

A good place to start your search is Dark Sky Finder [https://darksitefinder.com/map/] or the International Dark-Sky Association [https://www.darksky.org/our-work/conservation/idsp/finder/]

MOBILE APPS

Dark Sky Finder has both Apple and Android friendly apps. It shows a color-coded map to help you navigate to dark skies near you. This is the same function as the online version but is with you as long as you have cell service.

From the image above you can compare the overview of California light pollution to that of the areas around Lake Tahoe and Yosemite. In the above figure take note of how the severity of light pollution (white/red is the highest level of pollution) around the major cities compares to the low light pollution levels around Yosemite National Park. This means you are going to have a much easier time photographing the night sky in Yosemite than in San Francisco. 

HOW TO CAPTURE YOUR FIRST ASTROPHOTOGRAPHY IMAGE

Now that you know how to find a dark sky, let’s examine how to capture your first night photograph.

MINIMUM EQUIPMENT LIST

In order to give yourself the best chance of capturing the night sky, you need at least the following pieces of equipment. 

1. Camera with the ability to capture acceptable images at ISO 1600 minimum
2. A lens with a maximum aperture of at least 2.8. I currently use a 12mm Rokinon f2.0. ***Note: Because my primary camera is a Sony a6000, which has an APS-C sized sensor, 12mm has the equivalent of an 18mm field of view for a “full-frame” sensor.  This is important to know when determining your maximum shutter speed as you’ll soon do. 
3. Tripod – A steady foundation to mount your camera. Any movement during your exposure will ruin your photo.
4. Flashlight, headlamp, etc. – Ideally, you want a light source that can create red light. Red light is better to work with at night because it preserves your night vision. 

NICE TO HAVE EQUIPMENT

1. Shutter release cable or remote trigger – Allows you to trigger your shutter without touching the camera. Again, this is about minimizing any camera vibration to give yourself the best opportunity to capture your night photographs.
2. Phone with Photopills app installed – The “Night Augmented Reality” function of this app really helps to refine your composition when you are at your chosen location.
3. Camping chair – You will probably be outside for hours. It’s nice to have a comfortable place to sit to watch the night sky.

SETTING UP YOUR CAMERA AND EQUIPMENT

For your best chance of success arrive at your planned site during the day. This will allow you to get the lay of the land, scout, and compose your scene. This is the same approach you use for any other landscape photograph. [insert DPM article link] Next, set up your tripod and securely mount your camera to match your desired composition. Finally, it is time to set up your camera in preparation for photographing the night sky.

CAMERA SETTINGS – A STARTING POINT

FOCUS YOUR LENS IN ADVANCE

With your composition set and the camera mounted securely to the tripod it is time to turn your attention to your camera’s settings. The first place I like to start is setting the focus point for the lens. I set my focus for the largest available aperture because that is the aperture that will gather the most light for my photograph. Focusing the lens in advance allows me to remove one item from my list of concerns after sunset. 

Your goal is to set a focus that allows you the best chance of capturing the elements in the foreground you find interesting as well as the stars, moon, or other celestial subjects. This usually means setting your focus near infinity. Then either tape the focus ring down or rubber band it in place. 

The purpose of “locking” your focus is to prevent human error. By human error, I mean bumping into things in the night. It is such a disappointment to think you have captured a really great image only to see it is not in focus when you load it on your computer afterward.

SHUTTER SPEED – CAPTURING SHARP IMAGES

To capture sharp astrophotography images you need to consider your shutter speed. As we discussed the Earth is rotating relative to the stars, so if your shutter speed is too slow the stars will be blurry. How do you know what shutter speed to use? The answer to this question requires a little math, but don’t worry, the calculation is straight forward. 

500 RULE

You are going to use the 500 RULE to estimate the max shutter speed you can use to keep the stars as sharp as possible. Using the 500 Rule you divide 500 by the (full-frame equivalent) focal length you plan to capture what you have imagined. (note – if you are using a “crop sensor” I recommend accounting for the equivalent focal length) 

What is a “full-frame” equivalent focal length? A full-frame focal length equivalent is a function of the difference in size between a full-frame sensor (one that is the same area as a 35mm negative) and a smaller sensor. For my Sony a6000, the size ratio is 1.5:1. This means that a full-frame sensor is 1.5 times the size as the sensor in my camera. What this means is that even though I am using a 12mm lens, the camera sees the full-frame equivalent of 18mm. (1.5x(12mm)=18mm). 

Therefore, according to the 500 Rule if I want to calculate the maximum shutter speed to achieve a sharp focus I need to divide 500 by 18. The result is 27.8 seconds. Keep in mind this is a rough estimate. Through trial and error, I have found the best results closer to 20-25 seconds. 

As I said, these are the parameters for my camera. I recommend taking the time to research your camera to determine what size sensor it uses so you can perform the calculations for yourself.

For more examples see the following table.

If you are interested in learning more, check out this article for a discussion of sensor sizes.

APERTURE

In the equipment section of this article, I mentioned you should choose a lens that has a maximum aperture of at least 2.8. Because you are working at night and have limits on the shutter speed you can use having a lens with a large aperture helps to collect more light. My personal lens has a maximum aperture of 2.0. If you don’t currently have a lens with this capability, rent one to try out. If you find that astrophotography is a passion then consider buying a suitable lens. 

ISO

The last camera setting is ISO. I saved this for last because I like to dial in the ideal shutter speed and aperture before setting ISO. With many astrophotography images under my belt, I know that I’m not satisfied with the image quality if I use an ISO greater than 1600. So, if I can achieve good exposure with a lower ISO that is always my preference. 

Keep in mind this is with my current camera and lens combination. I recently had the chance to work with the Sony a7rIII and found good results up to ISO 6400. This was my personal taste. Image quality is subjective. Only practice will help you decide the right combination for yourself.

Final step – Click!

Using either the remote shutter release or your camera’s self-timer, take your shot. Congratulations. You just captured your first astrophotography image.

Kicking it up a notch:

More than likely when you see the night sky in the back of your camera you will be hooked on astrophotography. If that is the case, you can start adding some of the following to your night photography adventures and post processing.

• Adding compositional elements
• Milky Way photography
• Light painting
• Star trails
• Compositing
• Editing your night photography

MORE MOTIVATION

If you enjoyed this discussion and are looking for a little more motivation, check out My Five Favorite Astrophotography Images of 2019.

THANK YOU

Thank you so much for sharing part of your day reading through this article. I hope you found it interesting and useful. I’d love to see what you create on your own astrophotography adventures. Feel free to share in the comments below.

Until next time, I’ll see you on the trail.