When photographing in low light the first rule everyone knows is use a tripod. Using said tripod generally gives you the freedom to slow your shutter speed down without creating blurry images that would otherwise happen if you were hand holding the camera. Another good reason to use a tripod is it affords you the ability to maintain a lower ISO in low light which in turn keeps the noise in your images minimal (raising your ISO to keep a faster shutter speed can have the disadvantage of introducing digital noise to images). Lastly, the tripod allows you to set your camera at just about any angle without you having to worry about your muscles getting sore while holding it for extended periods of time. But when photographing the night sky there is one major difference you need to know.
Raise the ISO as opposed to leaving it at 200 and compensating with a longer shutter speed (most people’s initial reflex). There are a couple of reasons we do this. First, raising the ISO will increase the sensitivity of your cameras sensor enabling it to record distance light from stars that even your eyes can not see. Second, the higher your raise your ISO the less need there is to leave your shutter open for more than 60 seconds. After about 30 to 60 seconds you will start to see the stars light trails in your image (some people like this effect but others would rather not see it).
The exact ISO setting you should use is typically determined by the camera you are using, more specifically the cameras age. Newer cameras can use an ISO setting as low as 800 while older cameras will need at least 1600. If your goal is to introduce light trails behind the stars then you can stick with a lower ISO setting and increase the shutter speed to over a minute.
Longer shutter speeds with lower ISO means more light trails like the photograph above (photo source: Wikipedia)
Bonus Tip: Change your white balance to tungsten in order to get the best results, auto white balance tends to look like crap (Cameras vary so if tungsten doesn’t float your boat give some others a try to pick the one that looks the best to you).
Have you had some success with Astrophotography (photographing the stars)? Want to brag about it? Submit your image and the settings and/or post processing method you used on the Submit an Article page under Photo Journal. If you liked this tip and want to save kittens then share it by clicking the social icons below. Enjoy.