The app uses photon accumulation in low-light conditions, so the number of frames per second may be quite low. This behaviour is not lag or a fault, but a necessary process that works around the physical limits of a standard phone camera. The final image quality also depends heavily on your specific mobile phone model and the amount of available ambient light. For the app to work correctly, it needs at least a minimal light source, such as a starry sky or moonlight outdoors. In complete darkness, such as an enclosed room without windows, the app will not be able to create an image. Conversely, in daylight or bright light, the screen will turn completely white because the sensor is oversaturated.