The Core offers three calibration modes: Silent Manual (“M”), Automatic (“A”) and Semi-Automatic (“H”). “A” mode implies calibration without user participation (process initiation, actuation of the shutter takes place automatically). In “H” mode, the user determines if calibration is required based on image quality. If calibration is needed, the operator uses the “Cal” button. In “M” mode, manual calibration is accomplished by pressing the “Cal” button when the lens cap is closed. “M” mode is recommended for hunting due to silent operation.