Star Stacker, an astrophotography app available for iOS, allows users to create star trail images and timelapses on their phone, computer or tablet. Michael Webb, the developer, posted about his latest creation on Reddit’s r/LandscapeAstro community. To demonstrate a final result from using the app, Webb posted the image, seen above, and explained how he achieved it in the post’s comments section.
Using a Sony a7R III camera and Rokinon 14mm M2 lens, Webb captured 170 15-second exposure images with an ISO of 640 and an F4.0 aperture. Webb then copied the 170 RAW files to his phone using an SD card adapter and stacked the images in the app. To be clear, you can also import JPEG, .tiff or .png images from your iPhone or iPad’s photo app into Star Stacker. Pixelmator was used to combine images of the foreground and stars together for a final product.
After importing your selected photos, you can start creating images or timelapses with the following effects:
- Full trails – shows every star at full brightness.
- Faded trails – stars get brighter as the process runs.
- Shooting star – similar to faded trails but the last image is brighter than the previous, giving off a shooting star effect.
- Warp mode – zooms into the image stack slowly creating a warped effect. This will also impact the foreground so post processing may be required if the images have the foreground included.
Astrophotographers typically take a series of images in the same place and stack them to reduce noise. Is 170 necessary? Likely not. This video from Milky Way Mike breaks explains how many photos you should stack and why.