It is possible that the camera is not calibrated properly as in the examples below.
To calibrate the device, go to “Options” > “Device” > “Calibration“.
- Remove the lid;
- Point the device to a clear, smooth and homogeneous surface (e.g.: a white wall, sheet of paper);
- Press the “Start” button and wait until the timer ends;
- If the camera is still not a complete circle you can manually adjust it using the arrow buttons;
- Press the save icon on the top right corner of the screen.
If the image still contains edges, restart the calibration.