Night Sky Photography
These days it is possible to take spectacular pictures of the night sky with regular cameras and equipment. For example, I took the above picture with a Canon 60D DSLR and an entry level 8mm fisheye lens (click on the picture to see a larger version). In this article I'll give you a few simple rules you need to follow to maximize the chances of getting breathtaking deep sky photographs.
Camera and Lens
You can't take a picture of the night sky with any camera, there are a few requirements:
- High ISO. The dark sky is, of course, very dark. A camera can only "see" into it in the highest ISO settings. The picture above was taken at ISO 1600.
- Long exposure times. Your camera must have a manual mode that can take very long exposures. The above picture was a 60 second exposure. Many cameras have a bulb exposure mode that is great for this. For Canon shooters Magic Lantern provides programmable exposure times in bulb mode, so you don't have to keep the shutter pressed.
- Wide angle lens. The larger the field of view the more of the sky you can capture. Pictures are more impressive when a long stretch of the Milky Way appears in the frame. A short lens also enables longer exposure times before stars show trails due to the rotation of the Earth.
- Tripod. You obviously need a tripod or some other form of support that can keep the camera fixed through the exposure.
Choosing the right location is one of the most important decisions to get a great picture. You need to be in a very dark place so that the camera can pick up more detail in the sky.
Unfortunately city lights prevent us from seeing much of the sky due to a phenomenon called light pollution. So you need to find a place that is away from populated areas. I took the above picture on a beach near Long Beach, Washington. Even though the night seemed near pitch dark to my eyes, you can see in the picture that there was some light pollution coming from the right.
The best time to take deep sky pictures is when the sky is completely dark and clear. You want to do this after sunset and on days when there is no moon, so that the only light comes from the stars.
There aren't any settings that are set in stone, my method is iterative. I begin with the following settings:
- Camera in manual mode.
- ISO as high as it can go.
- Lens set to its largest aperture (smallest f number).
- If using a zoom lens, set it to its wide end.
- Manual focus, set to infinity.
- Exposure time set according to the Rule of 600 to avoid star trails due to the Earth rotation. The rule can be stated as the following formula: exposure time (in seconds) = 600 / focal length.
Then I start taking pictures and refining the ISO and exposure times until I'm satisfied with the result. The idea is to use the smallest ISO (since the higher the ISO the higher the noise) and keep the exposure time near the value indicated by the rule of 600 to avoid star trails.
The picture that starts this article was taken with the following equipment and settings:
- Camera: Canon 60D with Magic Lantern installed.
- Lens: Rokinon 8mm fisheye f/3.5
- ISO: 1600
- Exposure time: 60 seconds, using Magic Lantern, since the 60D does not allow programmable exposure times longer than 30 seconds. I cheated a bit here, since the 8mm is equivalent to approximately 12mm on the Canon 60D's APS-C sized sensor, so the maximum time according to the 600 rule is 600/12 = 50 seconds.
I hope you find the instructions useful and get great night sky pictures. Let me know in the comments if you have any other tips or suggestions.