The optical calibration is performed by a chessboard of at least 5X5 chess within the FOV.
Put the chessboard as straight as possible, make sure that the first column shows only half chess as shown in the image, enter the size of the single chess in millimeters or in the unit of measurement set in Measure and then press calibrate; the system will automatically calibrate the image.
In some particularly difficult conditions the operation can take a few minutes.
If everything is correct, the rectified image will appear with calibration process errors in micrometers; a cursor indicator will give you a qualitative evaluation of the calibration just done.
Then you can save the calibration as file to be able to select it from the Camera settings.
If a zoom lens is used, the procedure must be repeated for each magnification value.