This applies to Single Sheet calibration only. The first stage automatic referencer has a very difficult task. It has to reference at least 10 points on each photo but at this stage the camera parameters are only rough estimates and the camera station orientations are rough also. The biggest problem usually results from cameras with high levels of lens distortion (common on wide angle lenses) because lens distortion is not yet solved for in this first stage referencing. Sometimes this problem can be resolved by using fewer photographs in the calibration. You can also reduce the number of photographs that every mark must be referenced on in stage 1. See the Camera Calibrator section in Preferences - Processing and Cameras, “Required number of photos to be referenced for each point in stage one”. In extreme cases a field calibration can be used to replace the calibration.