I’m trying to calibrate HDRs images that I build from LDRs images. I used a Nikon D90 camera and a Sigma 4.5mm fisheye lens. However, for the calibration process to be complete, I need information about the lens’s actual angle of view. The manufacturer indicates 180º, but I believe I need to check this real angle, I know it can be a little more or a little less.
In the methodology indicated by Pierson, it is recommended to use a panoramic rotation unit and a sliding plate on which the camera is set. However, our laboratory does not have this equipment.
I would like to know if someone who used this same lens has already measured the real angle of view and if this information is applied to all lenses of the same model?
Generally speaking, can I apply the actual angle of view information from another Sigma 4.5mm lens to my Sigma 4.5mm lens?
Thank you in advance