It is always a challenge to take a good noise free astrophotograph. Flat frame help getting rid of the impact sensor dust and vignetting thus improving the quality of the photo.
The app has no ads, no tracker, no non-sense and is super tiny.

To use this app you need to:
1. After taking the photo, do not move you lens or telescope
2. Open the Flat Frame app on you phone or table.
3. Cover the front of your lens or telescope with the screen of your phone or tablet.
4. Properly expose the photo so it is neither overexposed or underexposed.
5. Take several flat frames and done.
6. After done with taking flat frame, exit out the app otherwise the app will keep the screen on forever.