I have a wide angle camera, the specifications say it is around 150°, but to me seems more ~100° horizontal and ~80° vertical. Anyway, once calibrated these fields of view are reduced by ~20 degrees each.
This is true for both the values returned by cv::calibrationMatrixValues function and the rectified frames, in which relatively big external portions are cropped.
Is this behavior normal? If it is, can I avoid this problem using the newer Fisheye camera model? With Fisheye is it possible to know the measured FOVs? I cannot find something like fisheye::calibrationMatrixValues.