To facilitate a procedure for a camera to use a parameter of a P-iris lens, in a calibration method for the camera with the P-iris lens having an adjustable iris opening.

The calibration includes a step for adjusting a size of the iris opening between a first opening position and a second opening position, a step for recording a plurality of images during the adjusting, a step for analyzing the images, and a step for determining an iris opening, based on the analysis, that obtains a high quality image.