Star stacking is a commonly used technique among astrophotographers. It helps you to reduce noise and end up with better images of the night sky. But how many photos should you stack to get the best results? The answer isn’t as simple as “take X photos and stack them.” But, Michael Ver Sprill aka Milky Way Mike shares some tips to help you determine the ideal number of photos to stack.
As Mike notes, it doesn’t really come down to the number of photos, but to the length of time that you spend to create the final shot. The length of time is basically the shutter speed x the number of shots. Sounds a bit confusing, but here’s an example.
For the sake of the video, Mike shot 30 images and stacked them, showing the noise reduction between five stacked photos, and all 30 of them. The more images you stack, the more noise reduction you’ll get. But, between 20 and 30 stacked photos, the difference is less obvious, so Mike sticks with 20 photos in this case.
When he shot the photos in this example, Mike used 10s exposure. This means that the length of time for his final image was: 20 images x 10 seconds = 200 seconds. The trick is, in short, to find the optimal total length of time to create one stacked image. Then you can adjust the shutter speed and the number of photos around this value. Make sure to watch Mike’s video to see the examples, and it will definitely be easier to grasp the concept.