When there are sufficient 'good' points and photos in the project, and the camera optimization check box is checked in the Processing Dialog then the camera calibration process will run along with the global optimization.
In calibration PhotoModeler attempts to make minor adjustments to the camera parameters to account for changes in focal length, principal point and lens distortion as the camera lens is focused.
Camera Optimization (or calibration) can take serval forms. These are called Full, Field, Self, and Auto. Full calibration is when the project is set up as a specific Camera Calibration project. Field Calibrating is done during processing of a normal project (optimize the camera at same time as project data). Self-calibration is similar but can treat every photo’s camera parameter differently (see Self-Calibrating.), and Auto calibration is field calibration that is carried out concurrently with Smart Orientation.