Camera Calibration

Hi, I'm working on a project using the raspberry pi HQ camera with a 6 mm lens and I noticed something strange that I'd like to discuss. When calibrating the camera (fixed in position) in an environment with controlled lighting and a fixed size chess board calibration target I noticed that the closer I get with the imaging plane to the camera the bigger the reprojection error gets. I can think of a few interpretations but since I'm not completely …

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